[RFA] Convert observers to C++

Message ID 20171105013039.9135-1-tom@tromey.com
State New, archived
Headers

Commit Message

Tom Tromey Nov. 5, 2017, 1:30 a.m. UTC
  This converts observers from using a special source-generating script
to be plain C++.  This is the second version of this patch.  This one
takes advavantage of C++11 by using std::function and variadic
templates.

This patch will require a clean build, because observer.h now appears
in the source directory.  If this seems inconvenient, I could choose a
different name for the new hearer, like "gdb_observers.h".

Regression tested on the buildbot.

ChangeLog
2017-11-04  Tom Tromey  <tom@tromey.com>

	* observer.h (gdb_observers) <test_notification>: Remove.
	* observer.c: Include selftest.h.
	(test_notification): Now static.
	(test_first_observer, test_second_observer, test_third_observer)
	(test_first_notification_function)
	(test_second_notification_function)
	(test_third_notification_function): Renamed.  Now static.
	(check_counters, observer_self_tests): New function.
	(_initialize_observer): Register observer_self_tests.
	* ada-lang.c, ada-tasks.c, agent.c, aix-thread.c, annotate.c,
	arm-tdep.c, auto-load.c, auxv.c, break-catch-syscall.c,
	breakpoint.c, bsd-uthread.c, cli/cli-interp.c, cli/cli-setshow.c,
	corefile.c, dummy-frame.c, event-loop.c, event-top.c, exec.c,
	extension.c, frame.c, gdbarch.c, guile/scm-breakpoint.c,
	infcall.c, infcmd.c, inferior.c, inflow.c, infrun.c, jit.c,
	linux-tdep.c, linux-thread-db.c, m68klinux-tdep.c,
	mi/mi-cmd-break.c, mi/mi-interp.c, objfiles.c, ppc-linux-nat.c,
	ppc-linux-tdep.c, printcmd.c, procfs.c, python/py-breakpoint.c,
	python/py-finishbreakpoint.c, python/py-inferior.c,
	python/py-unwind.c, ravenscar-thread.c, record-btrace.c,
	record-full.c, record.c, regcache.c, remote.c, sol-thread.c,
	solib-aix.c, solib-spu.c, solib.c, spu-multiarch.c, spu-tdep.c,
	symfile-mem.c, symfile.c, symtab.c, thread.c, top.c, tracepoint.c,
	tui/tui-hooks.c, tui/tui-interp.c, valops.c: Update all users.
	* tui/tui-hooks.c (tui_bp_created_observer)
	(tui_bp_deleted_observer, tui_bp_modified_observer)
	(tui_inferior_exit_observer, tui_before_prompt_observer)
	(tui_normal_stop_observer, tui_register_changed_observer): Change
	type.
	* record-btrace.c (record_btrace_thread_observer): Change type.
	(_initialize_record_btrace): Initialize
	record_btrace_thread_observer.
	* observer.sh: Remove.
	* observer.h: New file.
	* observer.c (namespace gdb_observers): Define new objects.
	(observer_debug): Move into gdb_observers namespace.
	(struct observer, struct observer_list, xalloc_observer_list_node)
	(xfree_observer_list_node, generic_observer_attach)
	(generic_observer_detach, generic_observer_notify): Remove.
	(_initialize_observer): Update.
	Don't include observer.inc.
	* Makefile.in (generated_files): Remove observer.h, observer.inc.
	(clean mostlyclean): Likewise.
	(observer.h, observer.inc): Remove targets.
	* .gitignore: Remove observer.h.

doc/ChangeLog
2017-11-04  Tom Tromey  <tom@tromey.com>

	* observer.texi: Remove.

testsuite/ChangeLog
2017-11-04  Tom Tromey  <tom@tromey.com>

	* gdb.gdb/observer.exp: Remove.
---
 gdb/.gitignore                     |   1 -
 gdb/ChangeLog                      |  48 ++++++
 gdb/Makefile.in                    |  10 +-
 gdb/ada-lang.c                     |   6 +-
 gdb/ada-tasks.c                    |   4 +-
 gdb/agent.c                        |   2 +-
 gdb/aix-thread.c                   |   4 +-
 gdb/annotate.c                     |   6 +-
 gdb/arm-tdep.c                     |   2 +-
 gdb/auto-load.c                    |   4 +-
 gdb/auxv.c                         |   6 +-
 gdb/break-catch-syscall.c          |   2 +-
 gdb/breakpoint.c                   |  50 +++---
 gdb/bsd-uthread.c                  |   6 +-
 gdb/cli/cli-interp.c               |  18 +--
 gdb/cli/cli-setshow.c              |  10 +-
 gdb/corefile.c                     |   2 +-
 gdb/doc/ChangeLog                  |   4 +
 gdb/doc/observer.texi              | 313 -------------------------------------
 gdb/dummy-frame.c                  |   2 +-
 gdb/event-loop.c                   |   2 +-
 gdb/event-top.c                    |   2 +-
 gdb/exec.c                         |   2 +-
 gdb/extension.c                    |   2 +-
 gdb/frame.c                        |   2 +-
 gdb/gdbarch.c                      |   2 +-
 gdb/guile/scm-breakpoint.c         |   4 +-
 gdb/infcall.c                      |   4 +-
 gdb/infcmd.c                       |   2 +-
 gdb/inferior.c                     |  13 +-
 gdb/inflow.c                       |   2 +-
 gdb/infrun.c                       |  26 +--
 gdb/jit.c                          |   6 +-
 gdb/linux-tdep.c                   |   4 +-
 gdb/linux-thread-db.c              |   6 +-
 gdb/m68k-linux-tdep.c              |   2 +-
 gdb/mi/mi-cmd-break.c              |   4 +-
 gdb/mi/mi-interp.c                 |  56 +++----
 gdb/mi/mi-main.c                   |   8 +-
 gdb/objfiles.c                     |   2 +-
 gdb/observer.c                     | 284 ++++++++++++++++-----------------
 gdb/observer.h                     | 283 +++++++++++++++++++++++++++++++++
 gdb/observer.sh                    | 200 ------------------------
 gdb/ppc-linux-nat.c                |   2 +-
 gdb/ppc-linux-tdep.c               |   6 +-
 gdb/printcmd.c                     |   2 +-
 gdb/procfs.c                       |   2 +-
 gdb/python/py-breakpoint.c         |   6 +-
 gdb/python/py-finishbreakpoint.c   |   4 +-
 gdb/python/py-inferior.c           |  24 +--
 gdb/python/py-unwind.c             |   2 +-
 gdb/ravenscar-thread.c             |   2 +-
 gdb/record-btrace.c                |  18 ++-
 gdb/record-full.c                  |   2 +-
 gdb/record.c                       |   2 +-
 gdb/regcache.c                     |   5 +-
 gdb/remote.c                       |   8 +-
 gdb/sol-thread.c                   |   2 +-
 gdb/solib-aix.c                    |   2 +-
 gdb/solib-spu.c                    |   2 +-
 gdb/solib.c                        |   8 +-
 gdb/spu-multiarch.c                |   6 +-
 gdb/spu-tdep.c                     |   6 +-
 gdb/stack.c                        |   8 +-
 gdb/symfile-mem.c                  |   2 +-
 gdb/symfile.c                      |  14 +-
 gdb/symtab.c                       |   6 +-
 gdb/testsuite/ChangeLog            |   4 +
 gdb/testsuite/gdb.gdb/observer.exp | 143 -----------------
 gdb/thread.c                       |  18 +--
 gdb/top.c                          |   2 +-
 gdb/tracepoint.c                   |  16 +-
 gdb/tui/tui-hooks.c                |  65 ++++----
 gdb/tui/tui-interp.c               |  18 +--
 gdb/valops.c                       |   4 +-
 75 files changed, 752 insertions(+), 1077 deletions(-)
 delete mode 100644 gdb/doc/observer.texi
 create mode 100644 gdb/observer.h
 delete mode 100755 gdb/observer.sh
 delete mode 100644 gdb/testsuite/gdb.gdb/observer.exp
  

Comments

Pedro Alves Nov. 7, 2017, 3:48 p.m. UTC | #1
On 11/05/2017 01:30 AM, Tom Tromey wrote:
> This converts observers from using a special source-generating script
> to be plain C++.  This is the second version of this patch.  This one
> takes advavantage of C++11 by using std::function and variadic
> templates.
> 
> This patch will require a clean build, because observer.h now appears
> in the source directory.  If this seems inconvenient, I could choose a
> different name for the new hearer, like "gdb_observers.h".
> 
> Regression tested on the buildbot.
> 

Thanks!

Some comments below.  Most mild, but one I think points at a bug.

> diff --git a/gdb/doc/observer.texi b/gdb/doc/observer.texi
> deleted file mode 100644
> index 606ddfe536..0000000000
> --- a/gdb/doc/observer.texi
> +++ /dev/null
> @@ -1,313 +0,0 @@
> -@c -*-texinfo-*-
> -
> -@c This file is part of the GDB manual.
> -@c
> -@c Copyright (C) 2003-2017 Free Software Foundation, Inc.
> -@c
> -@c See the file gdbint.texinfo for copying conditions.
> -@c
> -@c Also, the @deftypefun lines from this file are processed into a
> -@c header file during the GDB build process.  Permission is granted
> -@c to redistribute and/or modify those lines under the terms of the
> -@c GNU General Public License as published by the Free Software
> -@c Foundation; either version 3 of the License, or (at your option)
> -@c any later version.
> -
> -@node GDB Observers
> -@appendix @value{GDBN} Currently available observers
> -
> -@section Implementation rationale
> -@cindex observers implementation rationale
> -
> -An @dfn{observer} is an entity which is interested in being notified
> -when GDB reaches certain states, or certain events occur in GDB.
> -The entity being observed is called the @dfn{subject}.  To receive
> -notifications, the observer attaches a callback to the subject.
> -One subject can have several observers.
> -
> -@file{observer.c} implements an internal generic low-level event
> -notification mechanism.  This generic event notification mechanism is
> -then re-used to implement the exported high-level notification
> -management routines for all possible notifications.
> -
> -The current implementation of the generic observer provides support
> -for contextual data.  This contextual data is given to the subject
> -when attaching the callback.  In return, the subject will provide
> -this contextual data back to the observer as a parameter of the
> -callback.
> -
> -Note that the current support for the contextual data is only partial,
> -as it lacks a mechanism that would deallocate this data when the
> -callback is detached.  This is not a problem so far, as this contextual
> -data is only used internally to hold a function pointer.  Later on, if
> -a certain observer needs to provide support for user-level contextual
> -data, then the generic notification mechanism will need to be
> -enhanced to allow the observer to provide a routine to deallocate the
> -data when attaching the callback.
> -
> -The observer implementation is also currently not reentrant.
> -In particular, it is therefore not possible to call the attach
> -or detach routines during a notification.
> -
> -@section Debugging
> -Observer notifications can be traced using the command @samp{set debug
> -observer 1} (@pxref{Debugging Output, , Optional messages about
> -internal happenings, gdb, Debugging with @var{GDBN}}).
> -
> -@section @code{normal_stop} Notifications
> -@cindex @code{normal_stop} observer
> -@cindex notification about inferior execution stop
> -
> -@value{GDBN} notifies all @code{normal_stop} observers when the
> -inferior execution has just stopped, the associated messages and
> -annotations have been printed, and the control is about to be returned
> -to the user.
> -
> -Note that the @code{normal_stop} notification is not emitted when
> -the execution stops due to a breakpoint, and this breakpoint has
> -a condition that is not met.  If the breakpoint has any associated
> -commands list, the commands are executed after the notification
> -is emitted.

Is all the documentation in this file preserved?  I couldn't find
where this paragraph was moved to, for example.



> +namespace gdb_observers
> +{
> +unsigned int observer_debug;
> +
> +observer<struct bpstats *, int> normal_stop ("normal_stop");

You don't need to duplicate the observer types here.
This should work:

  decltype (normal_stop) normal_stop ("normal_stop");

And then, you could even do:

 #define DEFINE_OBSERVER(OBSERVER_NAME) \
   decltype (OBSERVER_NAME) OBSERVER_NAME (#OBSERVER_NAME)

 DEFINE_OBSERVER (normal_stop);
 DEFINE_OBSERVER (end_stepping_range);
 ...

> +observer<enum gdb_signal> signal_received ("signal_received");
> +observer<> end_stepping_range ("end_stepping_range");
> +observer<enum gdb_signal> signal_exited ("signal_exited");
> +observer<int> exited ("exited");
> +observer<> no_history ("no_history");
> +observer<> sync_execution_done ("sync_execution_done");
> +observer<> command_error ("command_error");
> +observer<struct target_ops *> target_changed ("target_changed");
> +observer<> executable_changed ("executable_changed");
> +observer<struct target_ops *, int> inferior_created ("inferior_created");
> +observer<struct inferior *, int, const char *, const char *>
> +    record_changed ("record_changed");
> +observer<struct so_list *> solib_loaded ("solib_loaded");
> +observer<struct so_list *> solib_unloaded ("solib_unloaded");
> +observer<struct objfile *> new_objfile ("new_objfile");
> +observer<struct objfile *> free_objfile ("free_objfile");
> +observer<struct thread_info *> new_thread ("new_thread");
> +observer<struct thread_info *, int> thread_exit ("thread_exit");
> +observer<ptid_t> thread_stop_requested ("thread_stop_requested");
> +observer<ptid_t> target_resumed ("target_resumed");
> +observer<> about_to_proceed ("about_to_proceed");
> +observer<struct breakpoint *> breakpoint_created ("breakpoint_created");
> +observer<struct breakpoint *> breakpoint_deleted ("breakpoint_deleted");
> +observer<struct breakpoint *> breakpoint_modified ("breakpoint_modified");
> +observer<int, int> traceframe_changed ("traceframe_changed");
> +observer<struct gdbarch *> architecture_changed ("architecture_changed");
> +observer<ptid_t, ptid_t> thread_ptid_changed ("thread_ptid_changed");
> +observer<struct inferior *> inferior_added ("inferior_added");
> +observer<struct inferior *> inferior_appeared ("inferior_appeared");
> +observer<struct inferior *> inferior_exit ("inferior_exit");
> +observer<struct inferior *> inferior_removed ("inferior_removed");
> +observer<struct inferior *, CORE_ADDR, ssize_t, const bfd_byte *>
> +    memory_changed ("memory_changed");
> +observer<const char *> before_prompt ("before_prompt");
> +observer<> gdb_datadir_changed ("gdb_datadir_changed");
> +observer<const char *, const char *>
> +    command_param_changed ("command_param_changed");
> +observer<const struct trace_state_variable *> tsv_created ("tsv_created");
> +observer<const struct trace_state_variable *> tsv_deleted ("tsv_deleted");
> +observer<const struct trace_state_variable *> tsv_modified ("tsv_modified");
> +observer<ptid_t, CORE_ADDR> inferior_call_pre ("inferior_call_pre");
> +observer<ptid_t, CORE_ADDR> inferior_call_post ("inferior_call_post");
> +observer<struct frame_info *, int> register_changed ("register_changed");
> +observer<user_selected_what>
> +    user_selected_context_changed ("user_selected_context_changed");
> +
> +#ifdef GDB_SELF_TEST
> +

It'd be nicer if the self tests were under "namespace selftests",
IMHO.

OOC, is there some guideline you were following for preferring
"namespace gdb_observers" over, say, "namespace gdb::observers" ?
Just curiosity, don't feel the need to change anything.

> +// This observer is used for internal testing.
> +static observer<int> test_notification ("test_notification");
> +

You're going to hate me, but it'd be nice IMO if you
switched to use /**/ consistently throughout, per GCC/GDB
convention.

>  
> -void
> -observer_test_third_notification_function (int arg)
> +static void
> +show_observer_debug (struct ui_file *file, int from_tty,
> +		     struct cmd_list_element *c, const char *value)
>  {
> -  observer_test_third_observer++;
> +  fprintf_filtered (file, _("Observer debugging is %s.\n"), value);
>  }
>  
>  void
>  _initialize_observer (void)
>  {
>    add_setshow_zuinteger_cmd ("observer", class_maintenance,
> -			     &observer_debug, _("\
> +			     &gdb_observers::observer_debug, _("\
>  Set observer debugging."), _("\
>  Show observer debugging."), _("\
>  When non-zero, observer debugging is enabled."),
>  			     NULL,
>  			     show_observer_debug,
>  			     &setdebuglist, &showdebuglist);
> -}
>  
> -#include "observer.inc"
> +#if GDB_SELF_TEST
> +  selftests::register_test ("gdb_observers",
> +			    gdb_observers::observer_self_tests);
> +#endif
> +}
> diff --git a/gdb/observer.h b/gdb/observer.h
> new file mode 100644
> index 0000000000..b40f6334ad
> --- /dev/null
> +++ b/gdb/observer.h
> @@ -0,0 +1,283 @@
> +/* Observers
> +
> +   Copyright (C) 2016, 2017 Free Software Foundation, Inc.

Use year range: 2016-2017.

> +template<typename... T>
> +class observer
> +{
> +public:
> +
> +  typedef std::function<void(T...)> func_type;
> +
> +  /* The return type of attach, which can be passed to detach to
> +     remove a listener.  */
> +  typedef size_t token_type;
> +
> +  /* A "null" value of token_type that can be used as a
> +     sentinel.  */
> +  static const token_type null_token;
> +
> +  explicit observer (const char *name) : m_name (name)
> +  {
> +  }
> +
> +  DISABLE_COPY_AND_ASSIGN (observer);
> +
> +  token_type attach (const func_type &f)
> +  {
> +    m_observers.push_back (f);
> +    return m_observers.size () - 1;
> +  }
> +
> +  void detach (const token_type &f)
> +  {
> +    m_observers.erase (m_observers.begin () + f);

Hmm, this looks incorrect.  "attach" returns an index
as token.  And then detach uses "std::vector::erase()",
which removes the element at the index and then shifts
the rest of the elements left to fill in the space
left over by the removed element(s).  So that invalidates
all token after the element erased.

> +  }
> +
> +  void notify (T... args) const
> +  {
> +    if (observer_debug)
> +      fprintf_unfiltered (gdb_stdlog, "observer %s notify() called\n",
> +			  m_name);
> +    for (auto &&func : m_observers)
> +      func (args...);
> +  }
> +
> +private:
> +
> +  std::vector<func_type> m_observers;
> +  const char *m_name;
> +};
> +
> +template<typename... T>
> +const typename observer<T...>::token_type observer<T...>::null_token
> +    = (size_t) -1;
> +

This could be constexpr and then defined in-class, right?

> +/* The inferior has stopped for real.  The bs argument describes the
> +   breakpoints were are stopped at, if any.  Second argument
> +   print_frame non-zero means display the location where the
> +   inferior has stopped.  */
> +extern observer<struct bpstats *, int> normal_stop;
> +
> +/* The inferior was stopped by a signal.  */
> +extern observer<enum gdb_signal> signal_received;
> +
> +/* We are done with a step/next/si/ni command.  */
> +extern observer<> end_stepping_range;
> +
> +/* The inferior was terminated by a signal.  */
> +extern observer<enum gdb_signal> signal_exited;
> +
> +/* The inferior program is finished.  */
> +extern observer<int> exited;
> +
> +/* Reverse execution: target ran out of history info.  */
> +extern observer<> no_history;
> +
> +/* A synchronous command finished.  */
> +extern observer<> sync_execution_done;
> +
> +/* An error was caught while executing a command.  */
> +extern observer<> command_error;
> +
> +/* The target's register contents have changed.  */
> +extern observer<struct target_ops *> target_changed;
> +
> +/* The executable being debugged by GDB has changed: The user
> +   decided to debug a different program, or the program he was
> +   debugging has been modified since being loaded by the debugger
> +   (by being recompiled, for instance).  */
> +extern observer<> executable_changed;
> +
> +/* gdb has just connected to an inferior.  For 'run', gdb calls this
> +   observer while the inferior is still stopped at the entry-point
> +   instruction.  For 'attach' and 'core', gdb calls this observer
> +   immediately after connecting to the inferior, and before any
> +   information on the inferior has been printed.  */
> +extern observer<struct target_ops *, int> inferior_created;
> +
> +/* The status of process record for inferior inferior in gdb has
> +   changed.  The process record is started if started is true, and
> +   the process record is stopped if started is false.
> +
> +   When started is true, method indicates the short name of the
> +   method used for recording.  If the method supports multiple
> +   formats, format indicates which one is being used, otherwise it
> +   is NULL.  When started is false, they are both NULL.  */
> +extern observer<struct inferior *, int, const char *, const char *>
> +    record_changed;
> +
> +/* The shared library specified by solib has been loaded.  Note that
> +   when gdb calls this observer, the library's symbols probably
> +   haven't been loaded yet.  */
> +extern observer<struct so_list *> solib_loaded;
> +
> +/* The shared library specified by solib has been unloaded.  Note
> +   that when gdb calls this observer, the library's symbols have not
> +   been unloaded yet, and thus are still available.  */
> +extern observer<struct so_list *> solib_unloaded;
> +
> +/* The symbol file specified by objfile has been loaded.  Called
> +   with objfile equal to NULL to indicate previously loaded symbol
> +   table data has now been invalidated.  */
> +extern observer<struct objfile *> new_objfile;
> +
> +/* The object file specified by objfile is about to be freed.  */
> +extern observer<struct objfile *> free_objfile;
> +
> +/* The thread specified by t has been created.  */
> +extern observer<struct thread_info *> new_thread;
> +
> +/* The thread specified by t has exited.  The silent argument
> +   indicates that gdb is removing the thread from its tables without
> +   wanting to notify the user about it.  */
> +extern observer<struct thread_info *, int> thread_exit;
> +
> +/* An explicit stop request was issued to ptid.  If ptid equals
> +   minus_one_ptid, the request applied to all threads.  If
> +   ptid_is_pid(ptid) returns true, the request applied to all
> +   threads of the process pointed at by ptid.  Otherwise, the
> +   request applied to the single thread pointed at by ptid.  */
> +extern observer<ptid_t> thread_stop_requested;
> +
> +/* The target was resumed.  The ptid parameter specifies which
> +   thread was resume, and may be RESUME_ALL if all threads are
> +   resumed.  */
> +extern observer<ptid_t> target_resumed;
> +
> +/* The target is about to be proceeded.  */
> +extern observer<> about_to_proceed;
> +
> +/* A new breakpoint b has been created.  */
> +extern observer<struct breakpoint *> breakpoint_created;
> +
> +/* A breakpoint has been destroyed.  The argument b is the
> +   pointer to the destroyed breakpoint.  */
> +extern observer<struct breakpoint *> breakpoint_deleted;
> +
> +/* A breakpoint has been modified in some way.  The argument b
> +   is the modified breakpoint.  */
> +extern observer<struct breakpoint *> breakpoint_modified;
> +
> +/* The trace frame is changed to tfnum (e.g., by using the 'tfind'
> +   command).  If tfnum is negative, it means gdb resumes live
> +   debugging.  The number of the tracepoint associated with this
> +   traceframe is tpnum.  */
> +extern observer<int, int> traceframe_changed;
> +
> +/* The current architecture has changed.  The argument newarch is a
> +   pointer to the new architecture.  */
> +extern observer<struct gdbarch *> architecture_changed;
> +
> +/* The thread's ptid has changed.  The old_ptid parameter specifies
> +   the old value, and new_ptid specifies the new value.  */
> +extern observer<ptid_t, ptid_t> thread_ptid_changed;
> +
> +/* The inferior inf has been added to the list of inferiors.  At
> +   this point, it might not be associated with any process.  */
> +extern observer<struct inferior *> inferior_added;
> +
> +/* The inferior identified by inf has been attached to a
> +   process.  */
> +extern observer<struct inferior *> inferior_appeared;
> +
> +/* Either the inferior associated with inf has been detached from
> +   the process, or the process has exited.  */
> +extern observer<struct inferior *> inferior_exit;
> +
> +/* The inferior inf has been removed from the list of inferiors.
> +   This method is called immediately before freeing inf.  */
> +extern observer<struct inferior *> inferior_removed;
> +
> +/* Bytes from data to data + len have been written to the inferior
> +   at addr.  */
> +extern observer<struct inferior *, CORE_ADDR, ssize_t, const bfd_byte *>
> +    memory_changed;
> +
> +/* Called before a top-level prompt is displayed.  current_prompt is
> +   the current top-level prompt.  */
> +extern observer<const char *> before_prompt;
> +
> +/* Variable gdb_datadir has been set.  The value may not necessarily
> +   change.  */
> +extern observer<> gdb_datadir_changed;
> +
> +/* The parameter of some 'set' commands in console are changed.
> +   This method is called after a command 'set param value'.  param
> +   is the parameter of 'set' command, and value is the value of
> +   changed parameter.  */
> +extern observer<const char *, const char *> command_param_changed;
> +
> +/* The new trace state variable tsv is created.  */
> +extern observer<const struct trace_state_variable *> tsv_created;
> +
> +/* The trace state variable tsv is deleted.  If tsv is NULL, all
> +   trace state variables are deleted.  */
> +extern observer<const struct trace_state_variable *> tsv_deleted;
> +
> +/* The trace state value tsv is modified.  */
> +extern observer<const struct trace_state_variable *> tsv_modified;
> +
> +/* An inferior function at address is about to be called in thread
> +   thread.  */
> +extern observer<ptid_t, CORE_ADDR> inferior_call_pre;
> +
> +/* The inferior function at address has just been called.  This
> +   observer is called even if the inferior exits during the call.
> +   thread is the thread in which the function was called, which may
> +   be different from the current thread.  */
> +extern observer<ptid_t, CORE_ADDR> inferior_call_post;
> +
> +/* A register in the inferior has been modified by the gdb user.  */
> +extern observer<struct frame_info *, int> register_changed;
> +
> +/* The user-selected inferior, thread and/or frame has changed.  The
> +   user_select_what flag specifies if the inferior, thread and/or
> +   frame has changed.  */
> +extern observer<user_selected_what> user_selected_context_changed;

(I wonder about splitting core/lib from uses of the core.
I.e., defining the struct observer core mechanism in one
header, and then define the actual observers in a separate header.
I'm basically pondering about e.g., using observers under common/
or in gdbserver/.  Like e.g., "common/observer.h" and then
"gdb/observers.h" and "gdbserver/observers.h", etc.  But we can cross
that bridge when we get to it, too.)

Thanks,
Pedro Alves
  
Tom Tromey Feb. 10, 2018, 12:17 a.m. UTC | #2
>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:

Responding to some old-ish mail...

>> This converts observers from using a special source-generating script
>> to be plain C++.
[...]

>> -Note that the @code{normal_stop} notification is not emitted when
>> -the execution stops due to a breakpoint, and this breakpoint has
>> -a condition that is not met.  If the breakpoint has any associated
>> -commands list, the commands are executed after the notification
>> -is emitted.

Pedro> Is all the documentation in this file preserved?  I couldn't find
Pedro> where this paragraph was moved to, for example.

I've now moved this paragraph in particular into a comment.  The rest is
either preserved or not relevant (IMO).  I've added some comments to the
public methods of the class.

Pedro> And then, you could even do:
Pedro>  #define DEFINE_OBSERVER(OBSERVER_NAME) \
Pedro>    decltype (OBSERVER_NAME) OBSERVER_NAME (#OBSERVER_NAME)
Pedro>  DEFINE_OBSERVER (normal_stop);

I did this.

Pedro> It'd be nicer if the self tests were under "namespace selftests",
Pedro> IMHO.

Done.

Pedro> OOC, is there some guideline you were following for preferring
Pedro> "namespace gdb_observers" over, say, "namespace gdb::observers" ?
Pedro> Just curiosity, don't feel the need to change anything.

Nope.  I went ahead and moved it to gdb::observers, since it was easy.

Pedro> You're going to hate me, but it'd be nice IMO if you
Pedro> switched to use /**/ consistently throughout, per GCC/GDB
Pedro> convention.

I did this.  This was actually easy too.

>> +    m_observers.erase (m_observers.begin () + f);

Pedro> Hmm, this looks incorrect.  "attach" returns an index
Pedro> as token.  And then detach uses "std::vector::erase()",
Pedro> which removes the element at the index and then shifts
Pedro> the rest of the elements left to fill in the space
Pedro> left over by the removed element(s).  So that invalidates
Pedro> all token after the element erased.

Yes, thanks for catching this.

I figure that observers aren't very space-sensitive, so I just put a
counter into the observer and then put the value into the vector, like:

  std::vector<std::pair<size_t, func_type>> m_observers;

Pedro> This could be constexpr and then defined in-class, right?

Did it.

Pedro> (I wonder about splitting core/lib from uses of the core.
Pedro> I.e., defining the struct observer core mechanism in one
Pedro> header, and then define the actual observers in a separate header.
Pedro> I'm basically pondering about e.g., using observers under common/
Pedro> or in gdbserver/.  Like e.g., "common/observer.h" and then
Pedro> "gdb/observers.h" and "gdbserver/observers.h", etc.  But we can cross
Pedro> that bridge when we get to it, too.)

I did this.  Also I realized that calling the class "observer" is
somewhat wrong, as the callback is the observer -- so I made
common/observable.h and I renamed the class to "class observable".

I'm running this through the buildbot again and when it is working I
will re-submit it.

Tom
  
Pedro Alves Feb. 12, 2018, 6:37 p.m. UTC | #3
Hi Tom,

Thanks!

On 02/10/2018 12:17 AM, Tom Tromey wrote:

> 
>>> +    m_observers.erase (m_observers.begin () + f);
> 
> Pedro> Hmm, this looks incorrect.  "attach" returns an index
> Pedro> as token.  And then detach uses "std::vector::erase()",
> Pedro> which removes the element at the index and then shifts
> Pedro> the rest of the elements left to fill in the space
> Pedro> left over by the removed element(s).  So that invalidates
> Pedro> all token after the element erased.
> 
> Yes, thanks for catching this.
> 
> I figure that observers aren't very space-sensitive, so I just put a
> counter into the observer and then put the value into the vector, like:
> 
>   std::vector<std::pair<size_t, func_type>> m_observers;

My initial reaction was "but counter of what?", but I took a
look at the patch, and I see what you mean.  I'll say more in
response to your new patch.

> 
> Pedro> This could be constexpr and then defined in-class, right?
> 
> Did it.
> 
> Pedro> (I wonder about splitting core/lib from uses of the core.
> Pedro> I.e., defining the struct observer core mechanism in one
> Pedro> header, and then define the actual observers in a separate header.
> Pedro> I'm basically pondering about e.g., using observers under common/
> Pedro> or in gdbserver/.  Like e.g., "common/observer.h" and then
> Pedro> "gdb/observers.h" and "gdbserver/observers.h", etc.  But we can cross
> Pedro> that bridge when we get to it, too.)
> 
> I did this.  Also I realized that calling the class "observer" is
> somewhat wrong, as the callback is the observer -- so I made
> common/observable.h and I renamed the class to "class observable".

Yeah, the current documentation in master calls them "subjects":

/* An observer is an entity who is interested in being notified when GDB
   reaches certain states, or certain events occur in GDB.  The entity being
   observed is called the Subject.  To receive notifications, the observer
   attaches a callback to the subject.  One subject can have several
   observers.

though "observable" does seem better to me.  

Thanks,
Pedro Alves
  

Patch

diff --git a/gdb/.gitignore b/gdb/.gitignore
index e7e108768e..b9b2c6f2d1 100644
--- a/gdb/.gitignore
+++ b/gdb/.gitignore
@@ -21,7 +21,6 @@ 
 /jv-exp.c
 /m2-exp.c
 /objc-exp.c
-/observer.h
 /observer.inc
 /p-exp.c
 /rust-exp.c
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 1a68746faf..1a989cdef4 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1911,8 +1911,6 @@  generated_files = \
 	config.h \
 	gcore \
 	jit-reader.h \
-	observer.h \
-	observer.inc \
 	$(GNULIB_H) \
 	$(NAT_GENERATED_FILES)
 
@@ -2297,7 +2295,7 @@  tags: TAGS
 clean mostlyclean: $(CONFIG_CLEAN)
 	@$(MAKE) $(FLAGS_TO_PASS) DO=clean "DODIRS=$(CLEANDIRS)" subdir_do
 	rm -f *.o *.a $(ADD_FILES) *~ init.c-tmp init.l-tmp version.c-tmp
-	rm -f init.c version.c observer.h observer.inc
+	rm -f init.c version.c
 	rm -f gdb$(EXEEXT) core make.log
 	rm -f gdb[0-9]$(EXEEXT)
 	rm -f test-cp-name-parser$(EXEEXT)
@@ -2484,12 +2482,6 @@  version.c: Makefile version.in $(srcdir)/../bfd/version.h $(srcdir)/common/creat
 	$(SHELL) $(srcdir)/common/create-version.sh $(srcdir) \
 	    $(host_alias) $(target_alias) version.c
 
-observer.h: observer.sh doc/observer.texi
-	${srcdir}/observer.sh h ${srcdir}/doc/observer.texi observer.h
-
-observer.inc: observer.sh doc/observer.texi
-	${srcdir}/observer.sh inc ${srcdir}/doc/observer.texi observer.inc
-
 lint: $(LINTFILES)
 	$(LINT) $(INCLUDE_CFLAGS) $(LINTFLAGS) $(LINTFILES) \
 	   `echo $(DEPFILES) $(CONFIG_OBS) | sed 's/\.o /\.c /g'`
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index b8636e6347..cad304a05d 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -14123,9 +14123,9 @@  DWARF attribute."),
      NULL, xcalloc, xfree);
 
   /* The ada-lang observers.  */
-  observer_attach_new_objfile (ada_new_objfile_observer);
-  observer_attach_free_objfile (ada_free_objfile_observer);
-  observer_attach_inferior_exit (ada_inferior_exit);
+  gdb_observers::new_objfile.attach (ada_new_objfile_observer);
+  gdb_observers::free_objfile.attach (ada_free_objfile_observer);
+  gdb_observers::inferior_exit.attach (ada_inferior_exit);
 
   /* Setup various context-specific data.  */
   ada_inferior_data
diff --git a/gdb/ada-tasks.c b/gdb/ada-tasks.c
index e0070d5b9a..794d5d5790 100644
--- a/gdb/ada-tasks.c
+++ b/gdb/ada-tasks.c
@@ -1429,8 +1429,8 @@  _initialize_tasks (void)
   ada_tasks_inferior_data_handle = register_inferior_data ();
 
   /* Attach various observers.  */
-  observer_attach_normal_stop (ada_tasks_normal_stop_observer);
-  observer_attach_new_objfile (ada_tasks_new_objfile_observer);
+  gdb_observers::normal_stop.attach (ada_tasks_normal_stop_observer);
+  gdb_observers::new_objfile.attach (ada_tasks_new_objfile_observer);
 
   /* Some new commands provided by this module.  */
   add_info ("tasks", info_tasks_command,
diff --git a/gdb/agent.c b/gdb/agent.c
index c0f10aa702..100d3a000a 100644
--- a/gdb/agent.c
+++ b/gdb/agent.c
@@ -66,7 +66,7 @@  agent_new_objfile (struct objfile *objfile)
 void
 _initialize_agent (void)
 {
-  observer_attach_new_objfile (agent_new_objfile);
+  gdb_observers::new_objfile.attach (agent_new_objfile);
 
   add_setshow_enum_cmd ("agent", class_run,
 			can_use_agent_enum,
diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
index b5c9f3b782..7c765ff6a2 100644
--- a/gdb/aix-thread.c
+++ b/gdb/aix-thread.c
@@ -1838,11 +1838,11 @@  _initialize_aix_thread (void)
   complete_target_initialization (&aix_thread_ops);
 
   /* Notice when object files get loaded and unloaded.  */
-  observer_attach_new_objfile (new_objfile);
+  gdb_observers::new_objfile.attach (new_objfile);
 
   /* Add ourselves to inferior_created event chain.
      This is needed to enable the thread target on "attach".  */
-  observer_attach_inferior_created (aix_thread_inferior_created);
+  gdb_observers::inferior_created.attach (aix_thread_inferior_created);
 
   add_setshow_boolean_cmd ("aix-thread", class_maintenance, &debug_aix_thread,
 			   _("Set debugging of AIX thread module."),
diff --git a/gdb/annotate.c b/gdb/annotate.c
index 6a02f73299..f7b8858110 100644
--- a/gdb/annotate.c
+++ b/gdb/annotate.c
@@ -592,7 +592,7 @@  breakpoint_changed (struct breakpoint *b)
 void
 _initialize_annotate (void)
 {
-  observer_attach_breakpoint_created (breakpoint_changed);
-  observer_attach_breakpoint_deleted (breakpoint_changed);
-  observer_attach_breakpoint_modified (breakpoint_changed);
+  gdb_observers::breakpoint_created.attach (breakpoint_changed);
+  gdb_observers::breakpoint_deleted.attach (breakpoint_changed);
+  gdb_observers::breakpoint_modified.attach (breakpoint_changed);
 }
diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index 46b7888fc9..20f481c2d2 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -9558,7 +9558,7 @@  _initialize_arm_tdep (void)
     = register_objfile_data_with_cleanup (NULL, arm_objfile_data_free);
 
   /* Add ourselves to objfile event chain.  */
-  observer_attach_new_objfile (arm_exidx_new_objfile);
+  gdb_observers::new_objfile.attach (arm_exidx_new_objfile);
   arm_exidx_data_key
     = register_objfile_data_with_cleanup (NULL, arm_exidx_data_free);
 
diff --git a/gdb/auto-load.c b/gdb/auto-load.c
index 0ccef19491..4769277bf3 100644
--- a/gdb/auto-load.c
+++ b/gdb/auto-load.c
@@ -1568,7 +1568,7 @@  _initialize_auto_load (void)
     = register_program_space_data_with_cleanup (NULL,
 						auto_load_pspace_data_cleanup);
 
-  observer_attach_new_objfile (auto_load_new_objfile);
+  gdb_observers::new_objfile.attach (auto_load_new_objfile);
 
   add_setshow_boolean_cmd ("gdb-scripts", class_support,
 			   &auto_load_gdb_scripts, _("\
@@ -1678,7 +1678,7 @@  This options has security implications for untrusted inferiors."),
 				     show_auto_load_safe_path,
 				     auto_load_set_cmdlist_get (),
 				     auto_load_show_cmdlist_get ());
-  observer_attach_gdb_datadir_changed (auto_load_gdb_datadir_changed);
+  gdb_observers::gdb_datadir_changed.attach (auto_load_gdb_datadir_changed);
 
   cmd = add_cmd ("add-auto-load-safe-path", class_support,
 		 add_auto_load_safe_path,
diff --git a/gdb/auxv.c b/gdb/auxv.c
index 95cbeecd79..a14c83c54b 100644
--- a/gdb/auxv.c
+++ b/gdb/auxv.c
@@ -579,7 +579,7 @@  This is information provided by the operating system at program startup."));
     = register_inferior_data_with_cleanup (NULL, auxv_inferior_data_cleanup);
 
   /* Observers used to invalidate the auxv cache when needed.  */
-  observer_attach_inferior_exit (invalidate_auxv_cache_inf);
-  observer_attach_inferior_appeared (invalidate_auxv_cache_inf);
-  observer_attach_executable_changed (invalidate_auxv_cache);
+  gdb_observers::inferior_exit.attach (invalidate_auxv_cache_inf);
+  gdb_observers::inferior_appeared.attach (invalidate_auxv_cache_inf);
+  gdb_observers::executable_changed.attach (invalidate_auxv_cache);
 }
diff --git a/gdb/break-catch-syscall.c b/gdb/break-catch-syscall.c
index b0ed4d29f8..60523b825d 100644
--- a/gdb/break-catch-syscall.c
+++ b/gdb/break-catch-syscall.c
@@ -641,7 +641,7 @@  _initialize_break_catch_syscall (void)
 {
   initialize_syscall_catchpoint_ops ();
 
-  observer_attach_inferior_exit (clear_syscall_counts);
+  gdb_observers::inferior_exit.attach (clear_syscall_counts);
   catch_syscall_inferior_data
     = register_inferior_data_with_cleanup (NULL,
 					   catch_syscall_inferior_data_cleanup);
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index adc8950591..b369c6de8f 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -927,7 +927,7 @@  set_breakpoint_condition (struct breakpoint *b, const char *exp,
     }
   mark_breakpoint_modified (b);
 
-  observer_notify_breakpoint_modified (b);
+  gdb_observers::breakpoint_modified.notify (b);
 }
 
 /* Completion for the "condition" command.  */
@@ -1197,7 +1197,7 @@  breakpoint_set_commands (struct breakpoint *b,
   validate_commands_for_breakpoint (b, commands.get ());
 
   b->commands = std::move (commands);
-  observer_notify_breakpoint_modified (b);
+  gdb_observers::breakpoint_modified.notify (b);
 }
 
 /* Set the internal `silent' flag on the breakpoint.  Note that this
@@ -1211,7 +1211,7 @@  breakpoint_set_silent (struct breakpoint *b, int silent)
 
   b->silent = silent;
   if (old_silent != silent)
-    observer_notify_breakpoint_modified (b);
+    gdb_observers::breakpoint_modified.notify (b);
 }
 
 /* Set the thread for this breakpoint.  If THREAD is -1, make the
@@ -1224,7 +1224,7 @@  breakpoint_set_thread (struct breakpoint *b, int thread)
 
   b->thread = thread;
   if (old_thread != thread)
-    observer_notify_breakpoint_modified (b);
+    gdb_observers::breakpoint_modified.notify (b);
 }
 
 /* Set the task for this breakpoint.  If TASK is 0, make the
@@ -1237,7 +1237,7 @@  breakpoint_set_task (struct breakpoint *b, int task)
 
   b->task = task;
   if (old_task != task)
-    observer_notify_breakpoint_modified (b);
+    gdb_observers::breakpoint_modified.notify (b);
 }
 
 void
@@ -1294,7 +1294,7 @@  commands_command_1 (const char *arg, int from_tty,
 	 {
 	   validate_commands_for_breakpoint (b, cmd.get ());
 	   b->commands = cmd;
-	   observer_notify_breakpoint_modified (b);
+	   gdb_observers::breakpoint_modified.notify (b);
 	 }
      });
 
@@ -2695,7 +2695,7 @@  insert_bp_location (struct bp_location *bl,
 	    {
 	      /* See also: disable_breakpoints_in_shlibs.  */
 	      bl->shlib_disabled = 1;
-	      observer_notify_breakpoint_modified (bl->owner);
+	      gdb_observers::breakpoint_modified.notify (bl->owner);
 	      if (!*disabled_breaks)
 		{
 		  fprintf_unfiltered (tmp_error_stream, 
@@ -5364,7 +5364,7 @@  bpstat_check_breakpoint_conditions (bpstat bs, ptid_t ptid)
       bs->stop = 0;
       /* Increase the hit count even though we don't stop.  */
       ++(b->hit_count);
-      observer_notify_breakpoint_modified (b);
+      gdb_observers::breakpoint_modified.notify (b);
     }	
 }
 
@@ -5519,7 +5519,7 @@  bpstat_stop_status (const address_space *aspace,
 	  if (bs->stop)
 	    {
 	      ++(b->hit_count);
-	      observer_notify_breakpoint_modified (b);
+	      gdb_observers::breakpoint_modified.notify (b);
 
 	      /* We will stop here.  */
 	      if (b->disposition == disp_disable)
@@ -7685,7 +7685,7 @@  disable_breakpoints_in_unloaded_shlib (struct so_list *solib)
 	loc->inserted = 0;
 
 	/* This may cause duplicate notifications for the same breakpoint.  */
-	observer_notify_breakpoint_modified (b);
+	gdb_observers::breakpoint_modified.notify (b);
 
 	if (!disabled_shlib_breaks)
 	  {
@@ -7768,7 +7768,7 @@  disable_breakpoints_in_freed_objfile (struct objfile *objfile)
 	}
 
       if (bp_modified)
-	observer_notify_breakpoint_modified (b);
+	gdb_observers::breakpoint_modified.notify (b);
     }
 }
 
@@ -8302,7 +8302,7 @@  install_breakpoint (int internal, std::unique_ptr<breakpoint> &&arg, int update_
     set_tracepoint_count (breakpoint_count);
   if (!internal)
     mention (b);
-  observer_notify_breakpoint_created (b);
+  gdb_observers::breakpoint_created.notify (b);
 
   if (update_gll)
     update_global_location_list (UGLL_MAY_INSERT);
@@ -10051,7 +10051,7 @@  break_range_command (char *arg_in, int from_tty)
   b->loc->length = length;
 
   mention (b);
-  observer_notify_breakpoint_created (b);
+  gdb_observers::breakpoint_created.notify (b);
   update_global_location_list (UGLL_MAY_INSERT);
 }
 
@@ -11809,7 +11809,7 @@  download_tracepoint_locations (void)
       t = (struct tracepoint *) b;
       t->number_on_target = b->number;
       if (bp_location_downloaded)
-	observer_notify_breakpoint_modified (b);
+	gdb_observers::breakpoint_modified.notify (b);
     }
 }
 
@@ -13327,7 +13327,7 @@  delete_breakpoint (struct breakpoint *bpt)
      a problem in that process, we'll be asked to delete the half-created
      watchpoint.  In that case, don't announce the deletion.  */
   if (bpt->number)
-    observer_notify_breakpoint_deleted (bpt);
+    gdb_observers::breakpoint_deleted.notify (bpt);
 
   if (breakpoint_chain == bpt)
     breakpoint_chain = bpt->next;
@@ -13803,7 +13803,7 @@  update_breakpoint_locations (struct breakpoint *b,
   }
 
   if (!locations_are_equal (existing_locations, b->loc))
-    observer_notify_breakpoint_modified (b);
+    gdb_observers::breakpoint_modified.notify (b);
 }
 
 /* Find the SaL locations corresponding to the given LOCATION.
@@ -14100,7 +14100,7 @@  set_ignore_count (int bptnum, int count, int from_tty)
 			       "crossings of breakpoint %d."),
 			     count, bptnum);
 	}
-      observer_notify_breakpoint_modified (b);
+      gdb_observers::breakpoint_modified.notify (b);
       return;
     }
 
@@ -14241,7 +14241,7 @@  disable_breakpoint (struct breakpoint *bpt)
 
   update_global_location_list (UGLL_DONT_INSERT);
 
-  observer_notify_breakpoint_modified (bpt);
+  gdb_observers::breakpoint_modified.notify (bpt);
 }
 
 static void
@@ -14350,7 +14350,7 @@  enable_breakpoint_disp (struct breakpoint *bpt, enum bpdisp disposition,
   bpt->enable_count = count;
   update_global_location_list (UGLL_MAY_INSERT);
 
-  observer_notify_breakpoint_modified (bpt);
+  gdb_observers::breakpoint_modified.notify (bpt);
 }
 
 
@@ -14872,7 +14872,7 @@  static void
 trace_pass_set_count (struct tracepoint *tp, int count, int from_tty)
 {
   tp->pass_count = count;
-  observer_notify_breakpoint_modified (tp);
+  gdb_observers::breakpoint_modified.notify (tp);
   if (from_tty)
     printf_filtered (_("Setting tracepoint %d's passcount to %d\n"),
 		     tp->number, count);
@@ -15505,9 +15505,9 @@  _initialize_breakpoint (void)
 
   initialize_breakpoint_ops ();
 
-  observer_attach_solib_unloaded (disable_breakpoints_in_unloaded_shlib);
-  observer_attach_free_objfile (disable_breakpoints_in_freed_objfile);
-  observer_attach_memory_changed (invalidate_bp_value_on_memory_change);
+  gdb_observers::solib_unloaded.attach (disable_breakpoints_in_unloaded_shlib);
+  gdb_observers::free_objfile.attach (disable_breakpoints_in_freed_objfile);
+  gdb_observers::memory_changed.attach (invalidate_bp_value_on_memory_change);
 
   breakpoint_objfile_key
     = register_objfile_data_with_cleanup (NULL, free_breakpoint_objfile_data);
@@ -16058,6 +16058,6 @@  agent-printf \"printf format string\", arg1, arg2, arg3, ..., argn\n\
 
   automatic_hardware_breakpoints = 1;
 
-  observer_attach_about_to_proceed (breakpoint_about_to_proceed);
-  observer_attach_thread_exit (remove_threaded_breakpoints);
+  gdb_observers::about_to_proceed.attach (breakpoint_about_to_proceed);
+  gdb_observers::thread_exit.attach (remove_threaded_breakpoints);
 }
diff --git a/gdb/bsd-uthread.c b/gdb/bsd-uthread.c
index 8018f5a438..2a46946112 100644
--- a/gdb/bsd-uthread.c
+++ b/gdb/bsd-uthread.c
@@ -554,7 +554,7 @@  _initialize_bsd_uthread (void)
 
   bsd_uthread_data = gdbarch_data_register_pre_init (bsd_uthread_init);
 
-  observer_attach_inferior_created (bsd_uthread_inferior_created);
-  observer_attach_solib_loaded (bsd_uthread_solib_loaded);
-  observer_attach_solib_unloaded (bsd_uthread_solib_unloaded);
+  gdb_observers::inferior_created.attach (bsd_uthread_inferior_created);
+  gdb_observers::solib_loaded.attach (bsd_uthread_solib_loaded);
+  gdb_observers::solib_unloaded.attach (bsd_uthread_solib_unloaded);
 }
diff --git a/gdb/cli/cli-interp.c b/gdb/cli/cli-interp.c
index 609a419fe8..63347b2053 100644
--- a/gdb/cli/cli-interp.c
+++ b/gdb/cli/cli-interp.c
@@ -465,14 +465,14 @@  _initialize_cli_interp (void)
   interp_factory_register (INTERP_CONSOLE, cli_interp_factory);
 
   /* If changing this, remember to update tui-interp.c as well.  */
-  observer_attach_normal_stop (cli_on_normal_stop);
-  observer_attach_end_stepping_range (cli_on_end_stepping_range);
-  observer_attach_signal_received (cli_on_signal_received);
-  observer_attach_signal_exited (cli_on_signal_exited);
-  observer_attach_exited (cli_on_exited);
-  observer_attach_no_history (cli_on_no_history);
-  observer_attach_sync_execution_done (cli_on_sync_execution_done);
-  observer_attach_command_error (cli_on_command_error);
-  observer_attach_user_selected_context_changed
+  gdb_observers::normal_stop.attach (cli_on_normal_stop);
+  gdb_observers::end_stepping_range.attach (cli_on_end_stepping_range);
+  gdb_observers::signal_received.attach (cli_on_signal_received);
+  gdb_observers::signal_exited.attach (cli_on_signal_exited);
+  gdb_observers::exited.attach (cli_on_exited);
+  gdb_observers::no_history.attach (cli_on_no_history);
+  gdb_observers::sync_execution_done.attach (cli_on_sync_execution_done);
+  gdb_observers::command_error.attach (cli_on_command_error);
+  gdb_observers::user_selected_context_changed.attach
     (cli_on_user_selected_context_changed);
 }
diff --git a/gdb/cli/cli-setshow.c b/gdb/cli/cli-setshow.c
index f89d2681ba..0e9fad095d 100644
--- a/gdb/cli/cli-setshow.c
+++ b/gdb/cli/cli-setshow.c
@@ -511,20 +511,20 @@  do_set_command (const char *arg, int from_tty, struct cmd_list_element *c)
 	case var_filename:
 	case var_optional_filename:
 	case var_enum:
-	  observer_notify_command_param_changed (name, *(char **) c->var);
+	  gdb_observers::command_param_changed.notify (name, *(char **) c->var);
 	  break;
 	case var_boolean:
 	  {
 	    const char *opt = *(int *) c->var ? "on" : "off";
 
-	    observer_notify_command_param_changed (name, opt);
+	    gdb_observers::command_param_changed.notify (name, opt);
 	  }
 	  break;
 	case var_auto_boolean:
 	  {
 	    const char *s = auto_boolean_enums[*(enum auto_boolean *) c->var];
 
-	    observer_notify_command_param_changed (name, s);
+	    gdb_observers::command_param_changed.notify (name, s);
 	  }
 	  break;
 	case var_uinteger:
@@ -533,7 +533,7 @@  do_set_command (const char *arg, int from_tty, struct cmd_list_element *c)
 	    char s[64];
 
 	    xsnprintf (s, sizeof s, "%u", *(unsigned int *) c->var);
-	    observer_notify_command_param_changed (name, s);
+	    gdb_observers::command_param_changed.notify (name, s);
 	  }
 	  break;
 	case var_integer:
@@ -543,7 +543,7 @@  do_set_command (const char *arg, int from_tty, struct cmd_list_element *c)
 	    char s[64];
 
 	    xsnprintf (s, sizeof s, "%d", *(int *) c->var);
-	    observer_notify_command_param_changed (name, s);
+	    gdb_observers::command_param_changed.notify (name, s);
 	  }
 	  break;
 	}
diff --git a/gdb/corefile.c b/gdb/corefile.c
index b9d95c07db..fada657f8d 100644
--- a/gdb/corefile.c
+++ b/gdb/corefile.c
@@ -408,7 +408,7 @@  write_memory_with_notification (CORE_ADDR memaddr, const bfd_byte *myaddr,
 				ssize_t len)
 {
   write_memory (memaddr, myaddr, len);
-  observer_notify_memory_changed (current_inferior (), memaddr, len, myaddr);
+  gdb_observers::memory_changed.notify (current_inferior (), memaddr, len, myaddr);
 }
 
 /* Store VALUE at ADDR in the inferior as a LEN-byte unsigned
diff --git a/gdb/doc/observer.texi b/gdb/doc/observer.texi
deleted file mode 100644
index 606ddfe536..0000000000
--- a/gdb/doc/observer.texi
+++ /dev/null
@@ -1,313 +0,0 @@ 
-@c -*-texinfo-*-
-
-@c This file is part of the GDB manual.
-@c
-@c Copyright (C) 2003-2017 Free Software Foundation, Inc.
-@c
-@c See the file gdbint.texinfo for copying conditions.
-@c
-@c Also, the @deftypefun lines from this file are processed into a
-@c header file during the GDB build process.  Permission is granted
-@c to redistribute and/or modify those lines under the terms of the
-@c GNU General Public License as published by the Free Software
-@c Foundation; either version 3 of the License, or (at your option)
-@c any later version.
-
-@node GDB Observers
-@appendix @value{GDBN} Currently available observers
-
-@section Implementation rationale
-@cindex observers implementation rationale
-
-An @dfn{observer} is an entity which is interested in being notified
-when GDB reaches certain states, or certain events occur in GDB.
-The entity being observed is called the @dfn{subject}.  To receive
-notifications, the observer attaches a callback to the subject.
-One subject can have several observers.
-
-@file{observer.c} implements an internal generic low-level event
-notification mechanism.  This generic event notification mechanism is
-then re-used to implement the exported high-level notification
-management routines for all possible notifications.
-
-The current implementation of the generic observer provides support
-for contextual data.  This contextual data is given to the subject
-when attaching the callback.  In return, the subject will provide
-this contextual data back to the observer as a parameter of the
-callback.
-
-Note that the current support for the contextual data is only partial,
-as it lacks a mechanism that would deallocate this data when the
-callback is detached.  This is not a problem so far, as this contextual
-data is only used internally to hold a function pointer.  Later on, if
-a certain observer needs to provide support for user-level contextual
-data, then the generic notification mechanism will need to be
-enhanced to allow the observer to provide a routine to deallocate the
-data when attaching the callback.
-
-The observer implementation is also currently not reentrant.
-In particular, it is therefore not possible to call the attach
-or detach routines during a notification.
-
-@section Debugging
-Observer notifications can be traced using the command @samp{set debug
-observer 1} (@pxref{Debugging Output, , Optional messages about
-internal happenings, gdb, Debugging with @var{GDBN}}).
-
-@section @code{normal_stop} Notifications
-@cindex @code{normal_stop} observer
-@cindex notification about inferior execution stop
-
-@value{GDBN} notifies all @code{normal_stop} observers when the
-inferior execution has just stopped, the associated messages and
-annotations have been printed, and the control is about to be returned
-to the user.
-
-Note that the @code{normal_stop} notification is not emitted when
-the execution stops due to a breakpoint, and this breakpoint has
-a condition that is not met.  If the breakpoint has any associated
-commands list, the commands are executed after the notification
-is emitted.
-
-The following interfaces are available to manage observers:
-
-@deftypefun extern struct observer *observer_attach_@var{event} (observer_@var{event}_ftype *@var{f})
-Using the function @var{f}, create an observer that is notified when
-ever @var{event} occurs, return the observer.
-@end deftypefun
-
-@deftypefun extern void observer_detach_@var{event} (struct observer *@var{observer});
-Remove @var{observer} from the list of observers to be notified when
-@var{event} occurs.
-@end deftypefun
-
-@deftypefun extern void observer_notify_@var{event} (void);
-Send a notification to all @var{event} observers.
-@end deftypefun
-
-The following observable events are defined:
-
-@deftypefun void normal_stop (struct bpstats *@var{bs}, int @var{print_frame})
-The inferior has stopped for real.  The  @var{bs} argument describes
-the breakpoints were are stopped at, if any.  Second argument
-@var{print_frame} non-zero means display the location where the
-inferior has stopped.
-@end deftypefun
-
-@deftypefun void signal_received (enum gdb_signal @var{siggnal})
-The inferior was stopped by a signal.
-@end deftypefun
-
-@deftypefun void end_stepping_range (void)
-We are done with a step/next/si/ni command.
-@end deftypefun
-
-@deftypefun void signal_exited (enum gdb_signal @var{siggnal})
-The inferior was terminated by a signal.
-@end deftypefun
-
-@deftypefun void exited (int @var{exitstatus})
-The inferior program is finished.
-@end deftypefun
-
-@deftypefun void no_history (void)
-Reverse execution: target ran out of history info.
-@end deftypefun
-
-@deftypefun void sync_execution_done (void)
-A synchronous command finished.
-@end deftypefun
-
-@deftypefun void command_error (void)
-An error was caught while executing a command.
-@end deftypefun
-
-@deftypefun void target_changed (struct target_ops *@var{target})
-The target's register contents have changed.
-@end deftypefun
-
-@deftypefun void executable_changed (void)
-The executable being debugged by GDB has changed: The user decided
-to debug a different program, or the program he was debugging has
-been modified since being loaded by the debugger (by being recompiled,
-for instance).
-@end deftypefun
-
-@deftypefun void inferior_created (struct target_ops *@var{objfile}, int @var{from_tty})
-@value{GDBN} has just connected to an inferior.  For @samp{run},
-@value{GDBN} calls this observer while the inferior is still stopped
-at the entry-point instruction.  For @samp{attach} and @samp{core},
-@value{GDBN} calls this observer immediately after connecting to the
-inferior, and before any information on the inferior has been printed.
-@end deftypefun
-
-@deftypefun void record_changed (struct inferior *@var{inferior}, int @var{started}, const char *@var{method}, const char *@var{format})
-The status of process record for inferior @var{inferior} in
-@value{GDBN} has changed.  The process record is started if
-@var{started} is true, and the process record is stopped if
-@var{started} is false.
-
-When @var{started} is true, @var{method} indicates the short name of the method
-used for recording.  If the method supports multiple formats, @var{format}
-indicates which one is being used, otherwise it is NULL.  When @var{started} is
-false, they are both NULL.
-@end deftypefun
-
-@deftypefun void solib_loaded (struct so_list *@var{solib})
-The shared library specified by @var{solib} has been loaded.  Note that
-when @value{GDBN} calls this observer, the library's symbols probably
-haven't been loaded yet.
-@end deftypefun
-
-@deftypefun void solib_unloaded (struct so_list *@var{solib})
-The shared library specified by @var{solib} has been unloaded.
-Note that when @value{GDBN} calls this observer, the library's
-symbols have not been unloaded yet, and thus are still available.
-@end deftypefun
-
-@deftypefun void new_objfile (struct objfile *@var{objfile})
-The symbol file specified by @var{objfile} has been loaded.
-Called with @var{objfile} equal to @code{NULL} to indicate
-previously loaded symbol table data has now been invalidated.
-@end deftypefun
-
-@deftypefun void free_objfile (struct objfile *@var{objfile})
-The object file specified by @var{objfile} is about to be freed.
-@end deftypefun
-
-@deftypefun void new_thread (struct thread_info *@var{t})
-The thread specified by @var{t} has been created.
-@end deftypefun
-
-@deftypefun void thread_exit (struct thread_info *@var{t}, int @var{silent})
-The thread specified by @var{t} has exited.  The @var{silent} argument
-indicates that @value{GDBN} is removing the thread from its tables
-without wanting to notify the user about it.
-@end deftypefun
-
-@deftypefun void thread_stop_requested (ptid_t @var{ptid})
-An explicit stop request was issued to @var{ptid}.  If @var{ptid}
-equals @var{minus_one_ptid}, the request applied to all threads.  If
-@code{ptid_is_pid(ptid)} returns true, the request applied to all
-threads of the process pointed at by @var{ptid}.  Otherwise, the
-request applied to the single thread pointed at by @var{ptid}.
-@end deftypefun
-
-@deftypefun void target_resumed (ptid_t @var{ptid})
-The target was resumed.  The @var{ptid} parameter specifies which
-thread was resume, and may be RESUME_ALL if all threads are resumed.
-@end deftypefun
-
-@deftypefun void about_to_proceed (void)
-The target is about to be proceeded.
-@end deftypefun
-
-@deftypefun void breakpoint_created (struct breakpoint *@var{b})
-A new breakpoint @var{b} has been created.
-@end deftypefun
-
-@deftypefun void breakpoint_deleted (struct breakpoint *@var{b})
-A breakpoint has been destroyed.  The argument @var{b} is the
-pointer to the destroyed breakpoint.
-@end deftypefun
-
-@deftypefun void breakpoint_modified (struct breakpoint *@var{b})
-A breakpoint has been modified in some way.  The argument @var{b}
-is the modified breakpoint.
-@end deftypefun
-
-@deftypefun void traceframe_changed (int @var{tfnum}, int @var{tpnum})
-The trace frame is changed to @var{tfnum} (e.g., by using the
-@code{tfind} command).  If @var{tfnum} is negative, it means
-@value{GDBN} resumes live debugging.  The number of the tracepoint
-associated with this traceframe is @var{tpnum}.
-@end deftypefun
-
-@deftypefun void architecture_changed (struct gdbarch *@var{newarch})
-The current architecture has changed.  The argument @var{newarch} is
-a pointer to the new architecture.
-@end deftypefun
-
-@deftypefun void thread_ptid_changed (ptid_t @var{old_ptid}, ptid_t @var{new_ptid})
-The thread's ptid has changed.  The @var{old_ptid} parameter specifies
-the old value, and @var{new_ptid} specifies the new value.
-@end deftypefun
-
-@deftypefun void inferior_added (struct inferior *@var{inf})
-The inferior @var{inf} has been added to the list of inferiors.  At
-this point, it might not be associated with any process.
-@end deftypefun
-
-@deftypefun void inferior_appeared (struct inferior *@var{inf})
-The inferior identified by @var{inf} has been attached to a process.
-@end deftypefun
-
-@deftypefun void inferior_exit (struct inferior *@var{inf})
-Either the inferior associated with @var{inf} has been detached from the
-process, or the process has exited.
-@end deftypefun
-
-@deftypefun void inferior_removed (struct inferior *@var{inf})
-The inferior @var{inf} has been removed from the list of inferiors.
-This method is called immediately before freeing @var{inf}.
-@end deftypefun
-
-@deftypefun void memory_changed (struct inferior *@var{inferior}, CORE_ADDR @var{addr}, ssize_t @var{len}, const bfd_byte *@var{data})
-Bytes from @var{data} to @var{data} + @var{len} have been written
-to the @var{inferior} at @var{addr}.
-@end deftypefun
-
-@deftypefun void before_prompt (const char *@var{current_prompt})
-Called before a top-level prompt is displayed.  @var{current_prompt} is
-the current top-level prompt.
-@end deftypefun
-
-@deftypefun void gdb_datadir_changed (void)
-Variable gdb_datadir has been set.  The value may not necessarily change.
-@end deftypefun
-
-@deftypefun void command_param_changed (const char *@var{param}, const char *@var{value})
-The parameter of some @code{set} commands in console are changed.  This
-method is called after a command @code{set @var{param} @var{value}}.
-@var{param} is the parameter of @code{set} command, and @var{value}
-is the value of changed parameter.
-@end deftypefun
-
-@deftypefun void tsv_created (const struct trace_state_variable *@var{tsv})
-The new trace state variable @var{tsv} is created.
-@end deftypefun
-
-@deftypefun void tsv_deleted (const struct trace_state_variable *@var{tsv})
-The trace state variable @var{tsv} is deleted.  If @var{tsv} is
-@code{NULL}, all trace state variables are deleted.
-@end deftypefun
-
-@deftypefun void tsv_modified (const struct trace_state_variable *@var{tsv})
-The trace state value @var{tsv} is modified.
-@end deftypefun
-
-@deftypefun void inferior_call_pre (ptid_t @var{thread}, CORE_ADDR @var{address})
-An inferior function at @var{address} is about to be called in thread
-@var{thread}.
-@end deftypefun
-
-@deftypefun void inferior_call_post (ptid_t @var{thread}, CORE_ADDR @var{address})
-The inferior function at @var{address} has just been called.  This observer
-is called even if the inferior exits during the call.  @var{thread} is the
-thread in which the function was called, which may be different from the
-current thread.
-@end deftypefun
-
-@deftypefun void register_changed (struct frame_info *@var{frame}, int @var{regnum})
-A register in the inferior has been modified by the @value{GDBN} user.
-@end deftypefun
-
-@deftypefun void test_notification (int @var{somearg})
-This observer is used for internal testing.  Do not use.  
-See testsuite/gdb.gdb/observer.exp.
-@end deftypefun
-
-@deftypefun void user_selected_context_changed (user_selected_what @var{selection})
-The user-selected inferior, thread and/or frame has changed.  The user_select_what
-flag specifies if the inferior, thread and/or frame has changed.
-@end deftypefun
diff --git a/gdb/dummy-frame.c b/gdb/dummy-frame.c
index a08031ccec..dfd9b1ef60 100644
--- a/gdb/dummy-frame.c
+++ b/gdb/dummy-frame.c
@@ -424,5 +424,5 @@  _initialize_dummy_frame (void)
 	   _("Print the contents of the internal dummy-frame stack."),
 	   &maintenanceprintlist);
 
-  observer_attach_inferior_created (cleanup_dummy_frames);
+  gdb_observers::inferior_created.attach (cleanup_dummy_frames);
 }
diff --git a/gdb/event-loop.c b/gdb/event-loop.c
index 7304ca7a2a..5622c1b083 100644
--- a/gdb/event-loop.c
+++ b/gdb/event-loop.c
@@ -382,7 +382,7 @@  start_event_loop (void)
 	     get around to resetting the prompt, which leaves readline
 	     in a messed-up state.  Reset it here.  */
 	  current_ui->prompt_state = PROMPT_NEEDED;
-	  observer_notify_command_error ();
+	  gdb_observers::command_error.notify ();
 	  /* This call looks bizarre, but it is required.  If the user
 	     entered a command that caused an error,
 	     after_char_processing_hook won't be called from
diff --git a/gdb/event-top.c b/gdb/event-top.c
index 43e2a27163..b2f23c0f2e 100644
--- a/gdb/event-top.c
+++ b/gdb/event-top.c
@@ -428,7 +428,7 @@  top_level_prompt (void)
 
   /* Give observers a chance of changing the prompt.  E.g., the python
      `gdb.prompt_hook' is installed as an observer.  */
-  observer_notify_before_prompt (get_prompt ());
+  gdb_observers::before_prompt.notify (get_prompt ());
 
   prompt = get_prompt ();
 
diff --git a/gdb/exec.c b/gdb/exec.c
index 326cfffe49..ac9eb59784 100644
--- a/gdb/exec.c
+++ b/gdb/exec.c
@@ -383,7 +383,7 @@  exec_file_attach (const char *filename, int from_tty)
     }
 
   bfd_cache_close_all ();
-  observer_notify_executable_changed ();
+  gdb_observers::executable_changed.notify ();
 }
 
 /*  Process the first arg in ARGS as the new exec file.
diff --git a/gdb/extension.c b/gdb/extension.c
index 4ffad038c9..59a26f72f4 100644
--- a/gdb/extension.c
+++ b/gdb/extension.c
@@ -1064,5 +1064,5 @@  ext_lang_before_prompt (const char *current_gdb_prompt)
 void
 _initialize_extension (void)
 {
-  observer_attach_before_prompt (ext_lang_before_prompt);
+  gdb_observers::before_prompt.attach (ext_lang_before_prompt);
 }
diff --git a/gdb/frame.c b/gdb/frame.c
index e643823716..2f042dbc92 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -2924,7 +2924,7 @@  _initialize_frame (void)
 
   frame_stash_create ();
 
-  observer_attach_target_changed (frame_observer_target_changed);
+  gdb_observers::target_changed.attach (frame_observer_target_changed);
 
   add_prefix_cmd ("backtrace", class_maintenance, set_backtrace_cmd, _("\
 Set backtrace specific variables.\n\
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 007392cd6a..6fb5541419 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -5435,7 +5435,7 @@  set_target_gdbarch (struct gdbarch *new_gdbarch)
   gdb_assert (new_gdbarch != NULL);
   gdb_assert (new_gdbarch->initialized_p);
   current_inferior ()->gdbarch = new_gdbarch;
-  observer_notify_architecture_changed (new_gdbarch);
+  gdb_observers::architecture_changed.notify (new_gdbarch);
   registers_changed ();
 }
 
diff --git a/gdb/guile/scm-breakpoint.c b/gdb/guile/scm-breakpoint.c
index ec75be589f..1f9c32a972 100644
--- a/gdb/guile/scm-breakpoint.c
+++ b/gdb/guile/scm-breakpoint.c
@@ -1326,8 +1326,8 @@  gdbscm_initialize_breakpoints (void)
   scm_set_smob_free (breakpoint_smob_tag, bpscm_free_breakpoint_smob);
   scm_set_smob_print (breakpoint_smob_tag, bpscm_print_breakpoint_smob);
 
-  observer_attach_breakpoint_created (bpscm_breakpoint_created);
-  observer_attach_breakpoint_deleted (bpscm_breakpoint_deleted);
+  gdb_observers::breakpoint_created.attach (bpscm_breakpoint_created);
+  gdb_observers::breakpoint_deleted.attach (bpscm_breakpoint_deleted);
 
   gdbscm_define_integer_constants (breakpoint_integer_constants, 1);
   gdbscm_define_functions (breakpoint_functions, 1);
diff --git a/gdb/infcall.c b/gdb/infcall.c
index b06758085d..9eb9263a7e 100644
--- a/gdb/infcall.c
+++ b/gdb/infcall.c
@@ -906,7 +906,7 @@  call_function_by_hand_dummy (struct value *function,
       target_values_type = values_type;
     }
 
-  observer_notify_inferior_call_pre (inferior_ptid, funaddr);
+  gdb_observers::inferior_call_pre.notify (inferior_ptid, funaddr);
 
   /* Determine the location of the breakpoint (and possibly other
      stuff) that the called function will return to.  The SPARC, for a
@@ -1186,7 +1186,7 @@  call_function_by_hand_dummy (struct value *function,
 
     e = run_inferior_call (sm, tp, real_pc);
 
-    observer_notify_inferior_call_post (call_thread_ptid, funaddr);
+    gdb_observers::inferior_call_post.notify (call_thread_ptid, funaddr);
 
     tp = find_thread_ptid (call_thread_ptid);
     if (tp != NULL)
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 49349c169e..5689ae3897 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -521,7 +521,7 @@  post_create_inferior (struct target_ops *target, int from_tty)
      if the now pushed target supports hardware watchpoints.  */
   breakpoint_re_set ();
 
-  observer_notify_inferior_created (target, from_tty);
+  gdb_observers::inferior_created.notify (target, from_tty);
 }
 
 /* Kill the inferior if already running.  This function is designed
diff --git a/gdb/inferior.c b/gdb/inferior.c
index ba8efe2342..473019e890 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -108,7 +108,7 @@  add_inferior_silent (int pid)
       last->next = inf;
     }
 
-  observer_notify_inferior_added (inf);
+  gdb_observers::inferior_added.notify (inf);
 
   if (pid != 0)
     inferior_appeared (inf, pid);
@@ -175,7 +175,7 @@  delete_inferior (struct inferior *todel)
   else
     inferior_list = inf->next;
 
-  observer_notify_inferior_removed (inf);
+  gdb_observers::inferior_removed.notify (inf);
 
   /* If this program space is rendered useless, remove it. */
   if (program_space_empty_p (inf->pspace))
@@ -205,7 +205,7 @@  exit_inferior_1 (struct inferior *inftoex, int silent)
 
   iterate_over_threads (delete_thread_of_inferior, &arg);
 
-  observer_notify_inferior_exit (inf);
+  gdb_observers::inferior_exit.notify (inf);
 
   inf->pid = 0;
   inf->fake_pid_p = 0;
@@ -271,7 +271,7 @@  inferior_appeared (struct inferior *inf, int pid)
   inf->has_exit_code = 0;
   inf->exit_code = 0;
 
-  observer_notify_inferior_appeared (inf);
+  gdb_observers::inferior_appeared.notify (inf);
 }
 
 void
@@ -700,7 +700,7 @@  inferior_command (const char *args, int from_tty)
 	  switch_to_thread (tp->ptid);
 	}
 
-      observer_notify_user_selected_context_changed
+      gdb_observers::user_selected_context_changed.notify
 	(USER_SELECTED_INFERIOR
 	 | USER_SELECTED_THREAD
 	 | USER_SELECTED_FRAME);
@@ -711,7 +711,8 @@  inferior_command (const char *args, int from_tty)
       switch_to_thread (null_ptid);
       set_current_program_space (inf->pspace);
 
-      observer_notify_user_selected_context_changed (USER_SELECTED_INFERIOR);
+      gdb_observers::user_selected_context_changed.notify
+	(USER_SELECTED_INFERIOR);
     }
 }
 
diff --git a/gdb/inflow.c b/gdb/inflow.c
index d54b8f8345..b934c83b09 100644
--- a/gdb/inflow.c
+++ b/gdb/inflow.c
@@ -826,7 +826,7 @@  _initialize_inflow (void)
   /* OK, figure out whether we have job control.  */
   have_job_control ();
 
-  observer_attach_inferior_exit (inflow_inferior_exit);
+  gdb_observers::inferior_exit.attach (inflow_inferior_exit);
 
   inflow_inferior_data
     = register_inferior_data_with_cleanup (NULL, inflow_inferior_data_cleanup);
diff --git a/gdb/infrun.c b/gdb/infrun.c
index d425664957..53ee80fa67 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -2906,7 +2906,7 @@  clear_proceed_status (int step)
       inferior->control.stop_soon = NO_STOP_QUIETLY;
     }
 
-  observer_notify_about_to_proceed ();
+  gdb_observers::about_to_proceed.notify ();
 }
 
 /* Returns true if TP is still stopped at a breakpoint that needs
@@ -3817,7 +3817,7 @@  check_curr_ui_sync_execution_done (void)
       && !gdb_in_secondary_prompt_p (ui))
     {
       target_terminal::ours ();
-      observer_notify_sync_execution_done ();
+      gdb_observers::sync_execution_done.notify ();
       ui_register_input_event_handler (ui);
     }
 }
@@ -5070,7 +5070,7 @@  handle_inferior_event_1 (struct execution_control_state *ecs)
 	  /* Support the --return-child-result option.  */
 	  return_child_result_value = ecs->ws.value.integer;
 
-	  observer_notify_exited (ecs->ws.value.integer);
+	  gdb_observers::exited.notify (ecs->ws.value.integer);
 	}
       else
 	{
@@ -5099,7 +5099,7 @@  handle_inferior_event_1 (struct execution_control_state *ecs)
 Cannot fill $_exitsignal with the correct signal number.\n"));
 	    }
 
-	  observer_notify_signal_exited (ecs->ws.value.sig);
+	  gdb_observers::signal_exited.notify (ecs->ws.value.sig);
 	}
 
       gdb_flush (gdb_stdout);
@@ -5393,7 +5393,7 @@  Cannot fill $_exitsignal with the correct signal number.\n"));
       if (handle_stop_requested (ecs))
 	return;
 
-      observer_notify_no_history ();
+      gdb_observers::no_history.notify ();
       stop_waiting (ecs);
       return;
     }
@@ -6097,7 +6097,7 @@  handle_signal_stop (struct execution_control_state *ecs)
 	{
 	  /* The signal table tells us to print about this signal.  */
 	  target_terminal::ours_for_output ();
-	  observer_notify_signal_received (ecs->event_thread->suspend.stop_signal);
+	  gdb_observers::signal_received.notify (ecs->event_thread->suspend.stop_signal);
 	  target_terminal::inferior ();
 	}
 
@@ -8213,7 +8213,7 @@  normal_stop (void)
   update_thread_list ();
 
   if (last.kind == TARGET_WAITKIND_STOPPED && stopped_by_random_signal)
-    observer_notify_signal_received (inferior_thread ()->suspend.stop_signal);
+    gdb_observers::signal_received.notify (inferior_thread ()->suspend.stop_signal);
 
   /* As with the notification of thread events, we want to delay
      notifying the user that we've switched thread context until
@@ -8338,10 +8338,10 @@  normal_stop (void)
   /* Notify observers about the stop.  This is where the interpreters
      print the stop event.  */
   if (!ptid_equal (inferior_ptid, null_ptid))
-    observer_notify_normal_stop (inferior_thread ()->control.stop_bpstat,
+    gdb_observers::normal_stop.notify (inferior_thread ()->control.stop_bpstat,
 				 stop_print_frame);
   else
-    observer_notify_normal_stop (NULL, stop_print_frame);
+    gdb_observers::normal_stop.notify (NULL, stop_print_frame);
 
   annotate_stopped ();
 
@@ -9446,10 +9446,10 @@  enabled by default on some platforms."),
   inferior_ptid = null_ptid;
   target_last_wait_ptid = minus_one_ptid;
 
-  observer_attach_thread_ptid_changed (infrun_thread_ptid_changed);
-  observer_attach_thread_stop_requested (infrun_thread_stop_requested);
-  observer_attach_thread_exit (infrun_thread_thread_exit);
-  observer_attach_inferior_exit (infrun_inferior_exit);
+  gdb_observers::thread_ptid_changed.attach (infrun_thread_ptid_changed);
+  gdb_observers::thread_stop_requested.attach (infrun_thread_stop_requested);
+  gdb_observers::thread_exit.attach (infrun_thread_thread_exit);
+  gdb_observers::inferior_exit.attach (infrun_inferior_exit);
 
   /* Explicitly create without lookup, since that tries to create a
      value with a void typed value, and when we get here, gdbarch
diff --git a/gdb/jit.c b/gdb/jit.c
index 7538684f4c..b03f28cfe3 100644
--- a/gdb/jit.c
+++ b/gdb/jit.c
@@ -1511,9 +1511,9 @@  _initialize_jit (void)
 			     show_jit_debug,
 			     &setdebuglist, &showdebuglist);
 
-  observer_attach_inferior_created (jit_inferior_created);
-  observer_attach_inferior_exit (jit_inferior_exit_hook);
-  observer_attach_breakpoint_deleted (jit_breakpoint_deleted);
+  gdb_observers::inferior_created.attach (jit_inferior_created);
+  gdb_observers::inferior_exit.attach (jit_inferior_exit_hook);
+  gdb_observers::breakpoint_deleted.attach (jit_breakpoint_deleted);
 
   jit_objfile_data =
     register_objfile_data_with_cleanup (NULL, free_objfile_data);
diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index 24237b8d39..a5df69cfed 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -2503,8 +2503,8 @@  _initialize_linux_tdep (void)
   linux_inferior_data
     = register_inferior_data_with_cleanup (NULL, linux_inferior_data_cleanup);
   /* Observers used to invalidate the cache when needed.  */
-  observer_attach_inferior_exit (invalidate_linux_cache_inf);
-  observer_attach_inferior_appeared (invalidate_linux_cache_inf);
+  gdb_observers::inferior_exit.attach (invalidate_linux_cache_inf);
+  gdb_observers::inferior_appeared.attach (invalidate_linux_cache_inf);
 
   add_setshow_boolean_cmd ("use-coredump-filter", class_files,
 			   &use_coredump_filter, _("\
diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
index 453505b3d7..f8b4572949 100644
--- a/gdb/linux-thread-db.c
+++ b/gdb/linux-thread-db.c
@@ -988,7 +988,7 @@  thread_db_new_objfile (struct objfile *objfile)
   if (objfile != NULL
       /* libpthread with separate debug info has its debug info file already
 	 loaded (and notified without successful thread_db initialization)
-	 the time observer_notify_new_objfile is called for the library itself.
+	 the time gdb_observers::new_objfile.notify is called for the library itself.
 	 Static executables have their separate debug info loaded already
 	 before the inferior has started.  */
       && objfile->separate_debug_objfile_backlink == NULL
@@ -1781,10 +1781,10 @@  Usage: info auto-load libthread-db"),
 	   auto_load_info_cmdlist_get ());
 
   /* Add ourselves to objfile event chain.  */
-  observer_attach_new_objfile (thread_db_new_objfile);
+  gdb_observers::new_objfile.attach (thread_db_new_objfile);
 
   /* Add ourselves to inferior_created event chain.
      This is needed to handle debugging statically linked programs where
      the new_objfile observer won't get called for libpthread.  */
-  observer_attach_inferior_created (thread_db_inferior_created);
+  gdb_observers::inferior_created.attach (thread_db_inferior_created);
 }
diff --git a/gdb/m68k-linux-tdep.c b/gdb/m68k-linux-tdep.c
index c911f2d4ac..9c6082b6d9 100644
--- a/gdb/m68k-linux-tdep.c
+++ b/gdb/m68k-linux-tdep.c
@@ -426,5 +426,5 @@  _initialize_m68k_linux_tdep (void)
 {
   gdbarch_register_osabi (bfd_arch_m68k, 0, GDB_OSABI_LINUX,
 			  m68k_linux_init_abi);
-  observer_attach_inferior_created (m68k_linux_inferior_created);
+  gdb_observers::inferior_created.attach (m68k_linux_inferior_created);
 }
diff --git a/gdb/mi/mi-cmd-break.c b/gdb/mi/mi-cmd-break.c
index 833bdc09ca..3e926054b5 100644
--- a/gdb/mi/mi-cmd-break.c
+++ b/gdb/mi/mi-cmd-break.c
@@ -84,7 +84,7 @@  setup_breakpoint_reporting (void)
 {
   if (! mi_breakpoint_observers_installed)
     {
-      observer_attach_breakpoint_created (breakpoint_notify);
+      gdb_observers::breakpoint_created.attach (breakpoint_notify);
       mi_breakpoint_observers_installed = 1;
     }
 
@@ -393,7 +393,7 @@  mi_cmd_break_passcount (const char *command, char **argv, int argc)
   if (t)
     {
       t->pass_count = p;
-      observer_notify_breakpoint_modified (t);
+      gdb_observers::breakpoint_modified.notify (t);
     }
   else
     {
diff --git a/gdb/mi/mi-interp.c b/gdb/mi/mi-interp.c
index d845a9c1b3..4feba09a22 100644
--- a/gdb/mi/mi-interp.c
+++ b/gdb/mi/mi-interp.c
@@ -1354,33 +1354,33 @@  _initialize_mi_interp (void)
   interp_factory_register (INTERP_MI3, mi_interp_factory);
   interp_factory_register (INTERP_MI, mi_interp_factory);
 
-  observer_attach_signal_received (mi_on_signal_received);
-  observer_attach_end_stepping_range (mi_on_end_stepping_range);
-  observer_attach_signal_exited (mi_on_signal_exited);
-  observer_attach_exited (mi_on_exited);
-  observer_attach_no_history (mi_on_no_history);
-  observer_attach_new_thread (mi_new_thread);
-  observer_attach_thread_exit (mi_thread_exit);
-  observer_attach_inferior_added (mi_inferior_added);
-  observer_attach_inferior_appeared (mi_inferior_appeared);
-  observer_attach_inferior_exit (mi_inferior_exit);
-  observer_attach_inferior_removed (mi_inferior_removed);
-  observer_attach_record_changed (mi_record_changed);
-  observer_attach_normal_stop (mi_on_normal_stop);
-  observer_attach_target_resumed (mi_on_resume);
-  observer_attach_solib_loaded (mi_solib_loaded);
-  observer_attach_solib_unloaded (mi_solib_unloaded);
-  observer_attach_about_to_proceed (mi_about_to_proceed);
-  observer_attach_traceframe_changed (mi_traceframe_changed);
-  observer_attach_tsv_created (mi_tsv_created);
-  observer_attach_tsv_deleted (mi_tsv_deleted);
-  observer_attach_tsv_modified (mi_tsv_modified);
-  observer_attach_breakpoint_created (mi_breakpoint_created);
-  observer_attach_breakpoint_deleted (mi_breakpoint_deleted);
-  observer_attach_breakpoint_modified (mi_breakpoint_modified);
-  observer_attach_command_param_changed (mi_command_param_changed);
-  observer_attach_memory_changed (mi_memory_changed);
-  observer_attach_sync_execution_done (mi_on_sync_execution_done);
-  observer_attach_user_selected_context_changed
+  gdb_observers::signal_received.attach (mi_on_signal_received);
+  gdb_observers::end_stepping_range.attach (mi_on_end_stepping_range);
+  gdb_observers::signal_exited.attach (mi_on_signal_exited);
+  gdb_observers::exited.attach (mi_on_exited);
+  gdb_observers::no_history.attach (mi_on_no_history);
+  gdb_observers::new_thread.attach (mi_new_thread);
+  gdb_observers::thread_exit.attach (mi_thread_exit);
+  gdb_observers::inferior_added.attach (mi_inferior_added);
+  gdb_observers::inferior_appeared.attach (mi_inferior_appeared);
+  gdb_observers::inferior_exit.attach (mi_inferior_exit);
+  gdb_observers::inferior_removed.attach (mi_inferior_removed);
+  gdb_observers::record_changed.attach (mi_record_changed);
+  gdb_observers::normal_stop.attach (mi_on_normal_stop);
+  gdb_observers::target_resumed.attach (mi_on_resume);
+  gdb_observers::solib_loaded.attach (mi_solib_loaded);
+  gdb_observers::solib_unloaded.attach (mi_solib_unloaded);
+  gdb_observers::about_to_proceed.attach (mi_about_to_proceed);
+  gdb_observers::traceframe_changed.attach (mi_traceframe_changed);
+  gdb_observers::tsv_created.attach (mi_tsv_created);
+  gdb_observers::tsv_deleted.attach (mi_tsv_deleted);
+  gdb_observers::tsv_modified.attach (mi_tsv_modified);
+  gdb_observers::breakpoint_created.attach (mi_breakpoint_created);
+  gdb_observers::breakpoint_deleted.attach (mi_breakpoint_deleted);
+  gdb_observers::breakpoint_modified.attach (mi_breakpoint_modified);
+  gdb_observers::command_param_changed.attach (mi_command_param_changed);
+  gdb_observers::memory_changed.attach (mi_memory_changed);
+  gdb_observers::sync_execution_done.attach (mi_on_sync_execution_done);
+  gdb_observers::user_selected_context_changed.attach
     (mi_user_selected_context_changed);
 }
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index 480d2fdc80..abb3e24fe5 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -572,8 +572,8 @@  mi_cmd_thread_select (const char *command, char **argv, int argc)
   /* Notify if the thread has effectively changed.  */
   if (!ptid_equal (inferior_ptid, previous_ptid))
     {
-      observer_notify_user_selected_context_changed (USER_SELECTED_THREAD
-						     | USER_SELECTED_FRAME);
+      gdb_observers::user_selected_context_changed.notify
+	(USER_SELECTED_THREAD | USER_SELECTED_FRAME);
     }
 }
 
@@ -2085,8 +2085,8 @@  mi_execute_command (const char *cmd, int from_tty)
 
 	  if (report_change)
 	    {
-		observer_notify_user_selected_context_changed
-		  (USER_SELECTED_THREAD | USER_SELECTED_FRAME);
+	      gdb_observers::user_selected_context_changed.notify
+		(USER_SELECTED_THREAD | USER_SELECTED_FRAME);
 	    }
 	}
     }
diff --git a/gdb/objfiles.c b/gdb/objfiles.c
index edde399802..a1101c09f7 100644
--- a/gdb/objfiles.c
+++ b/gdb/objfiles.c
@@ -616,7 +616,7 @@  free_objfile_separate_debug (struct objfile *objfile)
 objfile::~objfile ()
 {
   /* First notify observers that this objfile is about to be freed.  */
-  observer_notify_free_objfile (this);
+  gdb_observers::free_objfile.notify (this);
 
   /* Free all separate debug objfiles.  */
   free_objfile_separate_debug (this);
diff --git a/gdb/observer.c b/gdb/observer.c
index c461cda288..21aa910523 100644
--- a/gdb/observer.c
+++ b/gdb/observer.c
@@ -17,199 +17,187 @@ 
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-/* An observer is an entity who is interested in being notified when GDB
-   reaches certain states, or certain events occur in GDB.  The entity being
-   observed is called the Subject.  To receive notifications, the observer
-   attaches a callback to the subject.  One subject can have several
-   observers.
-
-   This file implements an internal generic low-level event notification
-   mechanism based on the Observer paradigm described in the book "Design
-   Patterns".  This generic event notification mechansim is then re-used
-   to implement the exported high-level notification management routines
-   for all possible notifications.
-
-   The current implementation of the generic observer provides support
-   for contextual data.  This contextual data is given to the subject
-   when attaching the callback.  In return, the subject will provide
-   this contextual data back to the observer as a parameter of the
-   callback.
-
-   FIXME: The current support for the contextual data is only partial,
-   as it lacks a mechanism that would deallocate this data when the
-   callback is detached.  This is not a problem so far, as this contextual
-   data is only used internally to hold a function pointer.  Later on,
-   if a certain observer needs to provide support for user-level
-   contextual data, then the generic notification mechanism will need
-   need to be enhanced to allow the observer to provide a routine to
-   deallocate the data when attaching the callback.
-
-   This file is currently maintained by hand, but the long term plan
-   if the number of different notifications starts growing is to create
-   a new script (observer.sh) that would generate this file, and the
-   associated documentation.  */
-
 #include "defs.h"
 #include "observer.h"
 #include "command.h"
 #include "gdbcmd.h"
+#include "selftest.h"
+
+namespace gdb_observers
+{
+unsigned int observer_debug;
+
+observer<struct bpstats *, int> normal_stop ("normal_stop");
+observer<enum gdb_signal> signal_received ("signal_received");
+observer<> end_stepping_range ("end_stepping_range");
+observer<enum gdb_signal> signal_exited ("signal_exited");
+observer<int> exited ("exited");
+observer<> no_history ("no_history");
+observer<> sync_execution_done ("sync_execution_done");
+observer<> command_error ("command_error");
+observer<struct target_ops *> target_changed ("target_changed");
+observer<> executable_changed ("executable_changed");
+observer<struct target_ops *, int> inferior_created ("inferior_created");
+observer<struct inferior *, int, const char *, const char *>
+    record_changed ("record_changed");
+observer<struct so_list *> solib_loaded ("solib_loaded");
+observer<struct so_list *> solib_unloaded ("solib_unloaded");
+observer<struct objfile *> new_objfile ("new_objfile");
+observer<struct objfile *> free_objfile ("free_objfile");
+observer<struct thread_info *> new_thread ("new_thread");
+observer<struct thread_info *, int> thread_exit ("thread_exit");
+observer<ptid_t> thread_stop_requested ("thread_stop_requested");
+observer<ptid_t> target_resumed ("target_resumed");
+observer<> about_to_proceed ("about_to_proceed");
+observer<struct breakpoint *> breakpoint_created ("breakpoint_created");
+observer<struct breakpoint *> breakpoint_deleted ("breakpoint_deleted");
+observer<struct breakpoint *> breakpoint_modified ("breakpoint_modified");
+observer<int, int> traceframe_changed ("traceframe_changed");
+observer<struct gdbarch *> architecture_changed ("architecture_changed");
+observer<ptid_t, ptid_t> thread_ptid_changed ("thread_ptid_changed");
+observer<struct inferior *> inferior_added ("inferior_added");
+observer<struct inferior *> inferior_appeared ("inferior_appeared");
+observer<struct inferior *> inferior_exit ("inferior_exit");
+observer<struct inferior *> inferior_removed ("inferior_removed");
+observer<struct inferior *, CORE_ADDR, ssize_t, const bfd_byte *>
+    memory_changed ("memory_changed");
+observer<const char *> before_prompt ("before_prompt");
+observer<> gdb_datadir_changed ("gdb_datadir_changed");
+observer<const char *, const char *>
+    command_param_changed ("command_param_changed");
+observer<const struct trace_state_variable *> tsv_created ("tsv_created");
+observer<const struct trace_state_variable *> tsv_deleted ("tsv_deleted");
+observer<const struct trace_state_variable *> tsv_modified ("tsv_modified");
+observer<ptid_t, CORE_ADDR> inferior_call_pre ("inferior_call_pre");
+observer<ptid_t, CORE_ADDR> inferior_call_post ("inferior_call_post");
+observer<struct frame_info *, int> register_changed ("register_changed");
+observer<user_selected_what>
+    user_selected_context_changed ("user_selected_context_changed");
+
+#ifdef GDB_SELF_TEST
+
+// This observer is used for internal testing.
+static observer<int> test_notification ("test_notification");
+
+static int test_first_observer = 0;
+static int test_second_observer = 0;
+static int test_third_observer = 0;
 
-static unsigned int observer_debug;
 static void
-show_observer_debug (struct ui_file *file, int from_tty,
-		     struct cmd_list_element *c, const char *value)
+test_first_notification_function (int arg)
 {
-  fprintf_filtered (file, _("Observer debugging is %s.\n"), value);
+  test_first_observer++;
 }
 
-/* The internal generic observer.  */
-
-typedef void (generic_observer_notification_ftype) (const void *data,
-						    const void *args);
-
-struct observer
+static void
+test_second_notification_function (int arg)
 {
-  generic_observer_notification_ftype *notify;
-  /* No memory management needed for the following field for now.  */
-  void *data;
-};
-
-/* A list of observers, maintained by the subject.  A subject is
-   actually represented by its list of observers.  */
+  test_second_observer++;
+}
 
-struct observer_list
+static void
+test_third_notification_function (int arg)
 {
-  struct observer_list *next;
-  struct observer *observer;
-};
-
-/* Allocate a struct observer_list, intended to be used as a node
-   in the list of observers maintained by a subject.  */
+  test_third_observer++;
+}
 
-static struct observer_list *
-xalloc_observer_list_node (void)
+static void
+notify_check_counters (int one, int two, int three)
 {
-  struct observer_list *node = XNEW (struct observer_list);
-
-  node->observer = XNEW (struct observer);
-  return node;
+  // Reset.
+  test_first_observer = 0;
+  test_second_observer = 0;
+  test_third_observer = 0;
+  // Notify.
+  test_notification.notify (0);
+  // Check.
+  SELF_CHECK (one == test_first_observer);
+  SELF_CHECK (two == test_second_observer);
+  SELF_CHECK (three == test_third_observer);
 }
 
-/* The opposite of xalloc_observer_list_node, frees the memory for
-   the given node.  */
-
 static void
-xfree_observer_list_node (struct observer_list *node)
+observer_self_tests ()
 {
-  xfree (node->observer);
-  xfree (node);
-}
+  // First, try sending a notification without any observer attached.
+  notify_check_counters (0, 0, 0);
 
-/* Attach the callback NOTIFY to a SUBJECT.  The DATA is also stored,
-   in order for the subject to provide it back to the observer during
-   a notification.  */
+  observer<int>::token_type token1, token2, token3;
 
-static struct observer *
-generic_observer_attach (struct observer_list **subject,
-			 generic_observer_notification_ftype * notify,
-			 void *data)
-{
-  struct observer_list *observer_list = xalloc_observer_list_node ();
+  // Now, attach one observer, and send a notification.
+  token2 = test_notification.attach (&test_second_notification_function);
+  notify_check_counters (0, 1, 0);
 
-  observer_list->next = *subject;
-  observer_list->observer->notify = notify;
-  observer_list->observer->data = data;
-  *subject = observer_list;
+  // Remove the observer, and send a notification.
+  test_notification.detach (token2);
+  notify_check_counters (0, 0, 0);
 
-  return observer_list->observer;
-}
+  // With a new observer.
+  token1 = test_notification.attach (&test_first_notification_function);
+  notify_check_counters (1, 0, 0);
 
-/* Remove the given OBSERVER from the SUBJECT.  Once detached, OBSERVER
-   should no longer be used, as it is no longer valid.  */
+  // With 2 observers.
+  token2 = test_notification.attach (&test_second_notification_function);
+  notify_check_counters (1, 1, 0);
 
-static void
-generic_observer_detach (struct observer_list **subject,
-			 const struct observer *observer)
-{
-  struct observer_list *previous_node = NULL;
-  struct observer_list *current_node = *subject;
-
-  while (current_node != NULL)
-    {
-      if (current_node->observer == observer)
-	{
-	  if (previous_node != NULL)
-	    previous_node->next = current_node->next;
-	  else
-	    *subject = current_node->next;
-	  xfree_observer_list_node (current_node);
-	  return;
-	}
-      previous_node = current_node;
-      current_node = current_node->next;
-    }
-
-  /* We should never reach this point.  However, this should not be
-     a very serious error, so simply report a warning to the user.  */
-  warning (_("Failed to detach observer"));
-}
+  // With 3 observers.
+  token3 = test_notification.attach (&test_third_notification_function);
+  notify_check_counters (1, 1, 1);
 
-/* Send a notification to all the observers of SUBJECT.  ARGS is passed to
-   all observers as an argument to the notification callback.  */
+  // Remove middle observer.
+  test_notification.detach (token2);
+  notify_check_counters (1, 0, 1);
 
-static void
-generic_observer_notify (struct observer_list *subject, const void *args)
-{
-  struct observer_list *current_node = subject;
+  // Remove first observer.
+  test_notification.detach (token1);
+  notify_check_counters (0, 0, 1);
 
-  while (current_node != NULL)
-    {
-      (*current_node->observer->notify) (current_node->observer->data, args);
-      current_node = current_node->next;
-    }
-}
+  // Remove last observer.
+  test_notification.detach (token3);
+  notify_check_counters (0, 0, 0);
 
+  // Go back to 3 observers, and remove them in a different order...
+  token1 = test_notification.attach (&test_first_notification_function);
+  token2 = test_notification.attach (&test_second_notification_function);
+  token3 = test_notification.attach (&test_third_notification_function);
+  notify_check_counters (1, 1, 1);
 
-/* The following code is only used to unit-test the observers from our
-   testsuite.  DO NOT USE IT within observer.c (or anywhere else for
-   that matter)!  */
+  // Remove the third observer.
+  test_notification.detach (token3);
+  notify_check_counters (1, 1, 0);
 
-/* If we define these variables and functions as `static', the
-   compiler will optimize them out.  */
- 
-int observer_test_first_observer = 0;
-int observer_test_second_observer = 0;
-int observer_test_third_observer = 0;
+  // Remove the second observer.
+  test_notification.detach (token2);
+  notify_check_counters (1, 0, 0);
 
-void
-observer_test_first_notification_function (int arg)
-{
-  observer_test_first_observer++;
+  // Remove first observer, no more observers.
+  test_notification.detach (token1);
+  notify_check_counters (0, 0, 0);
 }
-
-void
-observer_test_second_notification_function (int arg)
-{
-  observer_test_second_observer++;
+#endif
 }
 
-void
-observer_test_third_notification_function (int arg)
+static void
+show_observer_debug (struct ui_file *file, int from_tty,
+		     struct cmd_list_element *c, const char *value)
 {
-  observer_test_third_observer++;
+  fprintf_filtered (file, _("Observer debugging is %s.\n"), value);
 }
 
 void
 _initialize_observer (void)
 {
   add_setshow_zuinteger_cmd ("observer", class_maintenance,
-			     &observer_debug, _("\
+			     &gdb_observers::observer_debug, _("\
 Set observer debugging."), _("\
 Show observer debugging."), _("\
 When non-zero, observer debugging is enabled."),
 			     NULL,
 			     show_observer_debug,
 			     &setdebuglist, &showdebuglist);
-}
 
-#include "observer.inc"
+#if GDB_SELF_TEST
+  selftests::register_test ("gdb_observers",
+			    gdb_observers::observer_self_tests);
+#endif
+}
diff --git a/gdb/observer.h b/gdb/observer.h
new file mode 100644
index 0000000000..b40f6334ad
--- /dev/null
+++ b/gdb/observer.h
@@ -0,0 +1,283 @@ 
+/* Observers
+
+   Copyright (C) 2016, 2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#if !defined (GDB_OBSERVER_H)
+#define GDB_OBSERVER_H
+
+#include <functional>
+#include <vector>
+
+struct bpstats;
+struct so_list;
+struct objfile;
+struct thread_info;
+struct inferior;
+struct trace_state_variable;
+
+namespace gdb_observers
+{
+extern unsigned int observer_debug;
+
+/* An observer is an entity which is interested in being notified
+   when GDB reaches certain states, or certain events occur in GDB.
+   The entity being observed is called the subject.  To receive
+   notifications, the observer attaches a callback to the subject.
+   One subject can have several observers.
+
+   The observer implementation is also currently not reentrant.  In
+   particular, it is therefore not possible to call the attach or
+   detach routines during a notification.  */
+
+template<typename... T>
+class observer
+{
+public:
+
+  typedef std::function<void(T...)> func_type;
+
+  /* The return type of attach, which can be passed to detach to
+     remove a listener.  */
+  typedef size_t token_type;
+
+  /* A "null" value of token_type that can be used as a
+     sentinel.  */
+  static const token_type null_token;
+
+  explicit observer (const char *name) : m_name (name)
+  {
+  }
+
+  DISABLE_COPY_AND_ASSIGN (observer);
+
+  token_type attach (const func_type &f)
+  {
+    m_observers.push_back (f);
+    return m_observers.size () - 1;
+  }
+
+  void detach (const token_type &f)
+  {
+    m_observers.erase (m_observers.begin () + f);
+  }
+
+  void notify (T... args) const
+  {
+    if (observer_debug)
+      fprintf_unfiltered (gdb_stdlog, "observer %s notify() called\n",
+			  m_name);
+    for (auto &&func : m_observers)
+      func (args...);
+  }
+
+private:
+
+  std::vector<func_type> m_observers;
+  const char *m_name;
+};
+
+template<typename... T>
+const typename observer<T...>::token_type observer<T...>::null_token
+    = (size_t) -1;
+
+/* The inferior has stopped for real.  The bs argument describes the
+   breakpoints were are stopped at, if any.  Second argument
+   print_frame non-zero means display the location where the
+   inferior has stopped.  */
+extern observer<struct bpstats *, int> normal_stop;
+
+/* The inferior was stopped by a signal.  */
+extern observer<enum gdb_signal> signal_received;
+
+/* We are done with a step/next/si/ni command.  */
+extern observer<> end_stepping_range;
+
+/* The inferior was terminated by a signal.  */
+extern observer<enum gdb_signal> signal_exited;
+
+/* The inferior program is finished.  */
+extern observer<int> exited;
+
+/* Reverse execution: target ran out of history info.  */
+extern observer<> no_history;
+
+/* A synchronous command finished.  */
+extern observer<> sync_execution_done;
+
+/* An error was caught while executing a command.  */
+extern observer<> command_error;
+
+/* The target's register contents have changed.  */
+extern observer<struct target_ops *> target_changed;
+
+/* The executable being debugged by GDB has changed: The user
+   decided to debug a different program, or the program he was
+   debugging has been modified since being loaded by the debugger
+   (by being recompiled, for instance).  */
+extern observer<> executable_changed;
+
+/* gdb has just connected to an inferior.  For 'run', gdb calls this
+   observer while the inferior is still stopped at the entry-point
+   instruction.  For 'attach' and 'core', gdb calls this observer
+   immediately after connecting to the inferior, and before any
+   information on the inferior has been printed.  */
+extern observer<struct target_ops *, int> inferior_created;
+
+/* The status of process record for inferior inferior in gdb has
+   changed.  The process record is started if started is true, and
+   the process record is stopped if started is false.
+
+   When started is true, method indicates the short name of the
+   method used for recording.  If the method supports multiple
+   formats, format indicates which one is being used, otherwise it
+   is NULL.  When started is false, they are both NULL.  */
+extern observer<struct inferior *, int, const char *, const char *>
+    record_changed;
+
+/* The shared library specified by solib has been loaded.  Note that
+   when gdb calls this observer, the library's symbols probably
+   haven't been loaded yet.  */
+extern observer<struct so_list *> solib_loaded;
+
+/* The shared library specified by solib has been unloaded.  Note
+   that when gdb calls this observer, the library's symbols have not
+   been unloaded yet, and thus are still available.  */
+extern observer<struct so_list *> solib_unloaded;
+
+/* The symbol file specified by objfile has been loaded.  Called
+   with objfile equal to NULL to indicate previously loaded symbol
+   table data has now been invalidated.  */
+extern observer<struct objfile *> new_objfile;
+
+/* The object file specified by objfile is about to be freed.  */
+extern observer<struct objfile *> free_objfile;
+
+/* The thread specified by t has been created.  */
+extern observer<struct thread_info *> new_thread;
+
+/* The thread specified by t has exited.  The silent argument
+   indicates that gdb is removing the thread from its tables without
+   wanting to notify the user about it.  */
+extern observer<struct thread_info *, int> thread_exit;
+
+/* An explicit stop request was issued to ptid.  If ptid equals
+   minus_one_ptid, the request applied to all threads.  If
+   ptid_is_pid(ptid) returns true, the request applied to all
+   threads of the process pointed at by ptid.  Otherwise, the
+   request applied to the single thread pointed at by ptid.  */
+extern observer<ptid_t> thread_stop_requested;
+
+/* The target was resumed.  The ptid parameter specifies which
+   thread was resume, and may be RESUME_ALL if all threads are
+   resumed.  */
+extern observer<ptid_t> target_resumed;
+
+/* The target is about to be proceeded.  */
+extern observer<> about_to_proceed;
+
+/* A new breakpoint b has been created.  */
+extern observer<struct breakpoint *> breakpoint_created;
+
+/* A breakpoint has been destroyed.  The argument b is the
+   pointer to the destroyed breakpoint.  */
+extern observer<struct breakpoint *> breakpoint_deleted;
+
+/* A breakpoint has been modified in some way.  The argument b
+   is the modified breakpoint.  */
+extern observer<struct breakpoint *> breakpoint_modified;
+
+/* The trace frame is changed to tfnum (e.g., by using the 'tfind'
+   command).  If tfnum is negative, it means gdb resumes live
+   debugging.  The number of the tracepoint associated with this
+   traceframe is tpnum.  */
+extern observer<int, int> traceframe_changed;
+
+/* The current architecture has changed.  The argument newarch is a
+   pointer to the new architecture.  */
+extern observer<struct gdbarch *> architecture_changed;
+
+/* The thread's ptid has changed.  The old_ptid parameter specifies
+   the old value, and new_ptid specifies the new value.  */
+extern observer<ptid_t, ptid_t> thread_ptid_changed;
+
+/* The inferior inf has been added to the list of inferiors.  At
+   this point, it might not be associated with any process.  */
+extern observer<struct inferior *> inferior_added;
+
+/* The inferior identified by inf has been attached to a
+   process.  */
+extern observer<struct inferior *> inferior_appeared;
+
+/* Either the inferior associated with inf has been detached from
+   the process, or the process has exited.  */
+extern observer<struct inferior *> inferior_exit;
+
+/* The inferior inf has been removed from the list of inferiors.
+   This method is called immediately before freeing inf.  */
+extern observer<struct inferior *> inferior_removed;
+
+/* Bytes from data to data + len have been written to the inferior
+   at addr.  */
+extern observer<struct inferior *, CORE_ADDR, ssize_t, const bfd_byte *>
+    memory_changed;
+
+/* Called before a top-level prompt is displayed.  current_prompt is
+   the current top-level prompt.  */
+extern observer<const char *> before_prompt;
+
+/* Variable gdb_datadir has been set.  The value may not necessarily
+   change.  */
+extern observer<> gdb_datadir_changed;
+
+/* The parameter of some 'set' commands in console are changed.
+   This method is called after a command 'set param value'.  param
+   is the parameter of 'set' command, and value is the value of
+   changed parameter.  */
+extern observer<const char *, const char *> command_param_changed;
+
+/* The new trace state variable tsv is created.  */
+extern observer<const struct trace_state_variable *> tsv_created;
+
+/* The trace state variable tsv is deleted.  If tsv is NULL, all
+   trace state variables are deleted.  */
+extern observer<const struct trace_state_variable *> tsv_deleted;
+
+/* The trace state value tsv is modified.  */
+extern observer<const struct trace_state_variable *> tsv_modified;
+
+/* An inferior function at address is about to be called in thread
+   thread.  */
+extern observer<ptid_t, CORE_ADDR> inferior_call_pre;
+
+/* The inferior function at address has just been called.  This
+   observer is called even if the inferior exits during the call.
+   thread is the thread in which the function was called, which may
+   be different from the current thread.  */
+extern observer<ptid_t, CORE_ADDR> inferior_call_post;
+
+/* A register in the inferior has been modified by the gdb user.  */
+extern observer<struct frame_info *, int> register_changed;
+
+/* The user-selected inferior, thread and/or frame has changed.  The
+   user_select_what flag specifies if the inferior, thread and/or
+   frame has changed.  */
+extern observer<user_selected_what> user_selected_context_changed;
+
+}
+
+#endif /* GDB_OBSERVER_H */
diff --git a/gdb/observer.sh b/gdb/observer.sh
deleted file mode 100755
index 49db6b8cef..0000000000
--- a/gdb/observer.sh
+++ /dev/null
@@ -1,200 +0,0 @@ 
-#!/bin/sh -e
-
-# Make certain that the script is not running in an internationalized
-# environment.
-LANG=C ; export LANG
-LC_ALL=C ; export LC_ALL
-
-if test $# -ne 3
-then
-    echo "Usage: $0 <h|inc> <observer.texi> <observer.out>" 1>&2
-    exit 0
-fi
-
-lang=$1 ; shift
-texi=$1 ; shift
-o=$1
-case $lang in
-  h) tmp=htmp ;;
-  inc) tmp=itmp ;;
-esac
-otmp="`echo $1 | sed -e 's,\.[^.]*$,,'`.$tmp"; shift
-echo "Creating ${otmp}" 1>&2
-rm -f ${otmp}
-
-# Can use any of the following: cat cmp cp diff echo egrep expr false
-# grep install-info ln ls mkdir mv pwd rm rmdir sed sleep sort tar
-# test touch true
-
-cat <<EOF >>${otmp}
-/* GDB Notifications to Observers.
-
-   Copyright (C) 2004-2017 Free Software Foundation, Inc.
-
-   This file is part of GDB.
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 3 of the License, or
-   (at your option) any later version.
-  
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-  
-   You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-   --
-
-   This file was generated using observer.sh and observer.texi.  */
-
-EOF
-
-
-case $lang in
-    h) cat <<EOF >>${otmp}
-#ifndef OBSERVER_H
-#define OBSERVER_H
-
-struct observer;
-struct bpstats;
-struct so_list;
-struct objfile;
-struct thread_info;
-struct inferior;
-struct trace_state_variable;
-EOF
-        ;;
-esac
-
-# We are about to set IFS=:, so DOS-style file names with a drive
-# letter and a colon will be in trouble.
-
-if test -n "$DJGPP"
-then
-     texi=`echo $texi | sed -e 's,^\([a-zA-Z]\):/,/dev/\1/,'`
-fi
-
-# generate a list of events that can be observed
-
-IFS=:
-sed -n '
-/@deftypefun void/{
-# Save original line for later processing into the actual parameter
-    h
-# Convert from: @deftypefun void EVENT (TYPE @var{PARAM},...)
-# to event and formals: EVENT:TYPE PARAM, ...:
-    s/^.* void \([a-z_][a-z_]*\) (\(.*\))$/\1:\2/
-    s/@var{//g
-    s/}//g
-# Switch to held
-    x
-# Convert from: @deftypefun void FUNC (TYPE @var{PARAM},...)
-# to actuals: PARAM, ...
-    s/^[^{]*[{]*//
-    s/[}]*[^}]*$//
-    s/}[^{]*{/, /g
-# Combine held (EVENT:TYPE PARAM, ...:) and pattern (PARAM, ...) into
-# FUNC:TYPE PARAM, ...:PARAM, ...
-    H
-    x
-    s/\n/:/g
-    p
-}
-' $texi | while read event formal actual
-do
-  case $lang in
-      h) cat <<EOF >>${otmp}
-
-/* ${event} notifications.  */
-
-typedef void (observer_${event}_ftype) (${formal});
-
-extern struct observer *observer_attach_${event} (observer_${event}_ftype *f);
-extern void observer_detach_${event} (struct observer *observer);
-extern void observer_notify_${event} (${formal});
-EOF
-	;;
-
-      inc)
-      	cat <<EOF >>${otmp}
-
-/* ${event} notifications.  */
-
-static struct observer_list *${event}_subject = NULL;
-
-EOF
-	if test "$formal" != "void"; then
-	    cat<<EOF >>${otmp}
-struct ${event}_args { `echo "${formal}" | sed -e 's/,/;/g'`; };
-
-EOF
-	fi
-	cat <<EOF >>${otmp}
-static void
-observer_${event}_notification_stub (const void *data, const void *args_data)
-{
-  observer_${event}_ftype *notify = (observer_${event}_ftype *) data;
-EOF
-
-	notify_args=`echo ${actual} | sed -e 's/\([a-z0-9_][a-z0-9_]*\)/args->\1/g'`
-
-	if test ! -z "${notify_args}"; then
-	    cat<<EOF >>${otmp}
-  const struct ${event}_args *args = (const struct ${event}_args *) args_data;
-EOF
-	fi
-	cat <<EOF >>${otmp}
-  notify (${notify_args});
-}
-
-struct observer *
-observer_attach_${event} (observer_${event}_ftype *f)
-{
-  return generic_observer_attach (&${event}_subject,
-				  &observer_${event}_notification_stub,
-				  (void *) f);
-}
-
-void
-observer_detach_${event} (struct observer *observer)
-{
-  generic_observer_detach (&${event}_subject, observer);
-}
-
-void
-observer_notify_${event} (${formal})
-{
-EOF
-	if test "$formal" != "void"; then
-	    cat<<EOF >>${otmp}
-  struct ${event}_args args;
-  `echo ${actual} | sed -e 's/\([a-z0-9_][a-z0-9_]*\)/args.\1 = \1/g'`;
-
-EOF
-	else
-	    echo "char *args = NULL;" >> ${otmp}
-	fi
-	cat<<EOF >>${otmp}
-  if (observer_debug)
-    fprintf_unfiltered (gdb_stdlog, "observer_notify_${event}() called\n");
-  generic_observer_notify (${event}_subject, &args);
-}
-EOF
-	;;
-    esac
-done
-
-
-case $lang in
-    h) cat <<EOF >>${otmp}
-
-#endif /* OBSERVER_H */
-EOF
-esac
-
-
-echo Moving ${otmp} to ${o}
-mv ${otmp} ${o}
diff --git a/gdb/ppc-linux-nat.c b/gdb/ppc-linux-nat.c
index f645221cb4..e6e0343fdf 100644
--- a/gdb/ppc-linux-nat.c
+++ b/gdb/ppc-linux-nat.c
@@ -2500,7 +2500,7 @@  _initialize_ppc_linux_nat (void)
   t->to_read_description = ppc_linux_read_description;
   t->to_auxv_parse = ppc_linux_auxv_parse;
 
-  observer_attach_thread_exit (ppc_linux_thread_exit);
+  gdb_observers::thread_exit.attach (ppc_linux_thread_exit);
 
   /* Register the target.  */
   linux_nat_add_target (t);
diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
index ee80a71c6b..060f3c7ca2 100644
--- a/gdb/ppc-linux-tdep.c
+++ b/gdb/ppc-linux-tdep.c
@@ -1828,9 +1828,9 @@  _initialize_ppc_linux_tdep (void)
                          ppc_linux_init_abi);
 
   /* Attach to observers to track __spe_current_active_context.  */
-  observer_attach_inferior_created (ppc_linux_spe_context_inferior_created);
-  observer_attach_solib_loaded (ppc_linux_spe_context_solib_loaded);
-  observer_attach_solib_unloaded (ppc_linux_spe_context_solib_unloaded);
+  gdb_observers::inferior_created.attach (ppc_linux_spe_context_inferior_created);
+  gdb_observers::solib_loaded.attach (ppc_linux_spe_context_solib_loaded);
+  gdb_observers::solib_unloaded.attach (ppc_linux_spe_context_solib_unloaded);
 
   /* Initialize the Linux target descriptions.  */
   initialize_tdesc_powerpc_32l ();
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index 4323475939..0ba1f77f74 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -2640,7 +2640,7 @@  _initialize_printcmd (void)
 
   current_display_number = -1;
 
-  observer_attach_free_objfile (clear_dangling_display_expressions);
+  gdb_observers::free_objfile.attach (clear_dangling_display_expressions);
 
   add_info ("address", info_address_command,
 	    _("Describe where symbol SYM is stored."));
diff --git a/gdb/procfs.c b/gdb/procfs.c
index fb3fa58e9f..27379b4ebd 100644
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -5270,7 +5270,7 @@  proc_untrace_sysexit_cmd (char *args, int from_tty)
 void
 _initialize_procfs (void)
 {
-  observer_attach_inferior_created (procfs_inferior_created);
+  gdb_observers::inferior_created.attach (procfs_inferior_created);
 
   add_com ("proc-trace-entry", no_class, proc_trace_sysentry_cmd,
 	   _("Give a trace of entries into the syscall."));
diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index 86719d1b6e..121f0ac651 100644
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -971,9 +971,9 @@  gdbpy_initialize_breakpoints (void)
 			      (PyObject *) &breakpoint_object_type) < 0)
     return -1;
 
-  observer_attach_breakpoint_created (gdbpy_breakpoint_created);
-  observer_attach_breakpoint_deleted (gdbpy_breakpoint_deleted);
-  observer_attach_breakpoint_modified (gdbpy_breakpoint_modified);
+  gdb_observers::breakpoint_created.attach (gdbpy_breakpoint_created);
+  gdb_observers::breakpoint_deleted.attach (gdbpy_breakpoint_deleted);
+  gdb_observers::breakpoint_modified.attach (gdbpy_breakpoint_modified);
 
   /* Add breakpoint types constants.  */
   for (i = 0; pybp_codes[i].name; ++i)
diff --git a/gdb/python/py-finishbreakpoint.c b/gdb/python/py-finishbreakpoint.c
index 204d818023..09b9b8b50f 100644
--- a/gdb/python/py-finishbreakpoint.c
+++ b/gdb/python/py-finishbreakpoint.c
@@ -416,8 +416,8 @@  gdbpy_initialize_finishbreakpoints (void)
 			      (PyObject *) &finish_breakpoint_object_type) < 0)
     return -1;
 
-  observer_attach_normal_stop (bpfinishpy_handle_stop);
-  observer_attach_inferior_exit (bpfinishpy_handle_exit);
+  gdb_observers::normal_stop.attach (bpfinishpy_handle_stop);
+  gdb_observers::inferior_exit.attach (bpfinishpy_handle_exit);
 
   return 0;
 }
diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
index 381586d82d..f18ae54072 100644
--- a/gdb/python/py-inferior.c
+++ b/gdb/python/py-inferior.c
@@ -926,18 +926,18 @@  gdbpy_initialize_inferior (void)
   infpy_inf_data_key =
     register_inferior_data_with_cleanup (NULL, py_free_inferior);
 
-  observer_attach_new_thread (add_thread_object);
-  observer_attach_thread_exit (delete_thread_object);
-  observer_attach_normal_stop (python_on_normal_stop);
-  observer_attach_target_resumed (python_on_resume);
-  observer_attach_inferior_call_pre (python_on_inferior_call_pre);
-  observer_attach_inferior_call_post (python_on_inferior_call_post);
-  observer_attach_memory_changed (python_on_memory_change);
-  observer_attach_register_changed (python_on_register_change);
-  observer_attach_inferior_exit (python_inferior_exit);
-  observer_attach_new_objfile (python_new_objfile);
-  observer_attach_inferior_added (python_new_inferior);
-  observer_attach_inferior_removed (python_inferior_deleted);
+  gdb_observers::new_thread.attach (add_thread_object);
+  gdb_observers::thread_exit.attach (delete_thread_object);
+  gdb_observers::normal_stop.attach (python_on_normal_stop);
+  gdb_observers::target_resumed.attach (python_on_resume);
+  gdb_observers::inferior_call_pre.attach (python_on_inferior_call_pre);
+  gdb_observers::inferior_call_post.attach (python_on_inferior_call_post);
+  gdb_observers::memory_changed.attach (python_on_memory_change);
+  gdb_observers::register_changed.attach (python_on_register_change);
+  gdb_observers::inferior_exit.attach (python_inferior_exit);
+  gdb_observers::new_objfile.attach (python_new_objfile);
+  gdb_observers::inferior_added.attach (python_new_inferior);
+  gdb_observers::inferior_removed.attach (python_inferior_deleted);
 
   membuf_object_type.tp_new = PyType_GenericNew;
   if (PyType_Ready (&membuf_object_type) < 0)
diff --git a/gdb/python/py-unwind.c b/gdb/python/py-unwind.c
index acfce7d96c..fc007581ca 100644
--- a/gdb/python/py-unwind.c
+++ b/gdb/python/py-unwind.c
@@ -656,7 +656,7 @@  gdbpy_initialize_unwind (void)
         &setdebuglist, &showdebuglist);
   pyuw_gdbarch_data
       = gdbarch_data_register_post_init (pyuw_gdbarch_data_init);
-  observer_attach_architecture_changed (pyuw_on_new_gdbarch);
+  gdb_observers::architecture_changed.attach (pyuw_on_new_gdbarch);
 
   if (PyType_Ready (&pending_frame_object_type) < 0)
     return -1;
diff --git a/gdb/ravenscar-thread.c b/gdb/ravenscar-thread.c
index 850b84d2b5..6e858b78c7 100644
--- a/gdb/ravenscar-thread.c
+++ b/gdb/ravenscar-thread.c
@@ -432,7 +432,7 @@  _initialize_ravenscar (void)
 
   /* Notice when the inferior is created in order to push the
      ravenscar ops if needed.  */
-  observer_attach_inferior_created (ravenscar_inferior_created);
+  gdb_observers::inferior_created.attach (ravenscar_inferior_created);
 
   complete_target_initialization (&ravenscar_ops);
 
diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index b7e379bc91..ec0bc72db5 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -45,7 +45,8 @@ 
 static struct target_ops record_btrace_ops;
 
 /* A new thread observer enabling branch tracing for the new thread.  */
-static struct observer *record_btrace_thread_observer;
+static gdb_observers::observer<struct thread_info *>::token_type
+  record_btrace_thread_observer;
 
 /* Memory access types used in set/show record btrace replay-memory-access.  */
 static const char replay_memory_access_read_only[] = "read-only";
@@ -177,7 +178,7 @@  record_btrace_auto_enable (void)
   DEBUG ("attach thread observer");
 
   record_btrace_thread_observer
-    = observer_attach_new_thread (record_btrace_enable_warn);
+    = gdb_observers::new_thread.attach (record_btrace_enable_warn);
 }
 
 /* Disable automatic tracing of new threads.  */
@@ -186,13 +187,13 @@  static void
 record_btrace_auto_disable (void)
 {
   /* The observer may have been detached, already.  */
-  if (record_btrace_thread_observer == NULL)
+  if (record_btrace_thread_observer == gdb_observers::new_thread.null_token)
     return;
 
   DEBUG ("detach thread observer");
 
-  observer_detach_new_thread (record_btrace_thread_observer);
-  record_btrace_thread_observer = NULL;
+  gdb_observers::new_thread.detach (record_btrace_thread_observer);
+  record_btrace_thread_observer = gdb_observers::new_thread.null_token;
 }
 
 /* The record-btrace async event handler function.  */
@@ -220,7 +221,7 @@  record_btrace_push_target (void)
   record_btrace_generating_corefile = 0;
 
   format = btrace_format_short_string (record_btrace_conf.format);
-  observer_notify_record_changed (current_inferior (), 1, "btrace", format);
+  gdb_observers::record_changed.notify (current_inferior (), 1, "btrace", format);
 }
 
 /* The to_open method of target record-btrace.  */
@@ -238,7 +239,8 @@  record_btrace_open (const char *args, int from_tty)
   if (!target_has_execution)
     error (_("The program is not being run."));
 
-  gdb_assert (record_btrace_thread_observer == NULL);
+  gdb_assert (record_btrace_thread_observer
+	      == gdb_observers::new_thread.null_token);
 
   disable_chain = make_cleanup (null_cleanup, NULL);
   ALL_NON_EXITED_THREADS (tp)
@@ -3143,4 +3145,6 @@  to see the actual buffer size."), NULL, show_record_pt_buffer_size_value,
 
   record_btrace_conf.bts.size = 64 * 1024;
   record_btrace_conf.pt.size = 16 * 1024;
+
+  record_btrace_thread_observer = gdb_observers::new_thread.null_token;
 }
diff --git a/gdb/record-full.c b/gdb/record-full.c
index 6fc29d6170..1db7e3a1f1 100644
--- a/gdb/record-full.c
+++ b/gdb/record-full.c
@@ -853,7 +853,7 @@  record_full_open (const char *name, int from_tty)
 
   record_full_init_record_breakpoints ();
 
-  observer_notify_record_changed (current_inferior (),  1, "full", NULL);
+  gdb_observers::record_changed.notify (current_inferior (),  1, "full", NULL);
 }
 
 /* "to_close" target method.  Close the process record target.  */
diff --git a/gdb/record.c b/gdb/record.c
index d1d75414e1..23467378b7 100644
--- a/gdb/record.c
+++ b/gdb/record.c
@@ -311,7 +311,7 @@  cmd_record_stop (const char *args, int from_tty)
   printf_unfiltered (_("Process record is stopped and all execution "
 		       "logs are deleted.\n"));
 
-  observer_notify_record_changed (current_inferior (), 0, NULL, NULL);
+  gdb_observers::record_changed.notify (current_inferior (), 0, NULL, NULL);
 }
 
 /* The "set record" command.  */
diff --git a/gdb/regcache.c b/gdb/regcache.c
index 571aba1c93..142531ac6d 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -1688,8 +1688,9 @@  _initialize_regcache (void)
   regcache_descr_handle
     = gdbarch_data_register_post_init (init_regcache_descr);
 
-  observer_attach_target_changed (regcache_observer_target_changed);
-  observer_attach_thread_ptid_changed (regcache::regcache_thread_ptid_changed);
+  gdb_observers::target_changed.attach (regcache_observer_target_changed);
+  gdb_observers::thread_ptid_changed.attach
+    (regcache::regcache_thread_ptid_changed);
 
   add_com ("flushregs", class_maintenance, reg_flush_command,
 	   _("Force gdb to flush its register cache (maintainer command)"));
diff --git a/gdb/remote.c b/gdb/remote.c
index 57dbd1e320..490089a1e2 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -3890,9 +3890,9 @@  print_one_stopped_thread (struct thread_info *thread)
       enum gdb_signal sig = ws->value.sig;
 
       if (signal_print_state (sig))
-	observer_notify_signal_received (sig);
+	gdb_observers::signal_received.notify (sig);
     }
-  observer_notify_normal_stop (NULL, 1);
+  gdb_observers::normal_stop.notify (NULL, 1);
 }
 
 /* Process all initial stop replies the remote side sent in response
@@ -14041,10 +14041,10 @@  _initialize_remote (void)
   add_target (&extended_remote_ops);
 
   /* Hook into new objfile notification.  */
-  observer_attach_new_objfile (remote_new_objfile);
+  gdb_observers::new_objfile.attach (remote_new_objfile);
   /* We're no longer interested in notification events of an inferior
      when it exits.  */
-  observer_attach_inferior_exit (discard_pending_stop_replies);
+  gdb_observers::inferior_exit.attach (discard_pending_stop_replies);
 
 #if 0
   init_remote_threadtests ();
diff --git a/gdb/sol-thread.c b/gdb/sol-thread.c
index c5219148bd..fa0249c097 100644
--- a/gdb/sol-thread.c
+++ b/gdb/sol-thread.c
@@ -1229,7 +1229,7 @@  _initialize_sol_thread (void)
 	   _("Show info on Solaris user threads."), &maintenanceinfolist);
 
   /* Hook into new_objfile notification.  */
-  observer_attach_new_objfile (sol_thread_new_objfile);
+  gdb_observers::new_objfile.attach (sol_thread_new_objfile);
   return;
 
  die:
diff --git a/gdb/solib-aix.c b/gdb/solib-aix.c
index de238e597b..6f1fddf827 100644
--- a/gdb/solib-aix.c
+++ b/gdb/solib-aix.c
@@ -788,7 +788,7 @@  _initialize_solib_aix (void)
 
   solib_aix_inferior_data_handle = register_inferior_data ();
 
-  observer_attach_normal_stop (solib_aix_normal_stop_observer);
+  gdb_observers::normal_stop.attach (solib_aix_normal_stop_observer);
 
   /* Debug this file's internals.  */
   add_setshow_boolean_cmd ("aix-solib", class_maintenance,
diff --git a/gdb/solib-spu.c b/gdb/solib-spu.c
index 886322d9bc..955572800d 100644
--- a/gdb/solib-spu.c
+++ b/gdb/solib-spu.c
@@ -545,7 +545,7 @@  spu_solib_loaded (struct so_list *so)
 void
 _initialize_spu_solib (void)
 {
-  observer_attach_solib_loaded (spu_solib_loaded);
+  gdb_observers::solib_loaded.attach (spu_solib_loaded);
   ocl_program_data_key = register_objfile_data ();
 }
 
diff --git a/gdb/solib.c b/gdb/solib.c
index f9f7217b7d..a483d614d4 100644
--- a/gdb/solib.c
+++ b/gdb/solib.c
@@ -841,7 +841,7 @@  update_solib_list (int from_tty)
 	{
 	  /* Notify any observer that the shared object has been
 	     unloaded before we remove it from GDB's tables.  */
-	  observer_notify_solib_unloaded (gdb);
+	  gdb_observers::solib_unloaded.notify (gdb);
 
 	  VEC_safe_push (char_ptr, current_program_space->deleted_solibs,
 			 xstrdup (gdb->so_name));
@@ -903,7 +903,7 @@  update_solib_list (int from_tty)
 
 	  /* Notify any observer that the shared object has been
 	     loaded now that we've added it to GDB's tables.  */
-	  observer_notify_solib_loaded (i);
+	  gdb_observers::solib_loaded.notify (i);
 	}
 
       /* If a library was not found, issue an appropriate warning
@@ -1211,7 +1211,7 @@  clear_solib (void)
       struct so_list *so = so_list_head;
 
       so_list_head = so->next;
-      observer_notify_solib_unloaded (so);
+      gdb_observers::solib_unloaded.notify (so);
       remove_target_sections (so);
       free_so (so);
     }
@@ -1615,7 +1615,7 @@  _initialize_solib (void)
 {
   solib_data = gdbarch_data_register_pre_init (solib_init);
 
-  observer_attach_free_objfile (remove_user_added_objfile);
+  gdb_observers::free_objfile.attach (remove_user_added_objfile);
 
   add_com ("sharedlibrary", class_files, sharedlibrary_command,
 	   _("Load shared object library symbols for files matching REGEXP."));
diff --git a/gdb/spu-multiarch.c b/gdb/spu-multiarch.c
index 392995900e..36cf41440f 100644
--- a/gdb/spu-multiarch.c
+++ b/gdb/spu-multiarch.c
@@ -410,8 +410,8 @@  _initialize_spu_multiarch (void)
   complete_target_initialization (&spu_ops);
 
   /* Install observers to watch for SPU objects.  */
-  observer_attach_inferior_created (spu_multiarch_inferior_created);
-  observer_attach_solib_loaded (spu_multiarch_solib_loaded);
-  observer_attach_solib_unloaded (spu_multiarch_solib_unloaded);
+  gdb_observers::inferior_created.attach (spu_multiarch_inferior_created);
+  gdb_observers::solib_loaded.attach (spu_multiarch_solib_loaded);
+  gdb_observers::solib_unloaded.attach (spu_multiarch_solib_unloaded);
 }
 
diff --git a/gdb/spu-tdep.c b/gdb/spu-tdep.c
index ecdc7fc439..0791491f40 100644
--- a/gdb/spu-tdep.c
+++ b/gdb/spu-tdep.c
@@ -2763,14 +2763,14 @@  _initialize_spu_tdep (void)
   register_gdbarch_init (bfd_arch_spu, spu_gdbarch_init);
 
   /* Add ourselves to objfile event chain.  */
-  observer_attach_new_objfile (spu_overlay_new_objfile);
+  gdb_observers::new_objfile.attach (spu_overlay_new_objfile);
   spu_overlay_data = register_objfile_data ();
 
   /* Install spu stop-on-load handler.  */
-  observer_attach_new_objfile (spu_catch_start);
+  gdb_observers::new_objfile.attach (spu_catch_start);
 
   /* Add ourselves to normal_stop event chain.  */
-  observer_attach_normal_stop (spu_attach_normal_stop);
+  gdb_observers::normal_stop.attach (spu_attach_normal_stop);
 
   /* Add root prefix command for all "set spu"/"show spu" commands.  */
   add_prefix_cmd ("spu", no_class, set_spu_command,
diff --git a/gdb/stack.c b/gdb/stack.c
index 42cb7369d1..3d7c9c1645 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -2276,7 +2276,7 @@  select_frame_command (char *level_exp, int from_tty)
 
   select_frame (parse_frame_specification (level_exp, NULL));
   if (get_selected_frame_if_set () != prev_frame)
-    observer_notify_user_selected_context_changed (USER_SELECTED_FRAME);
+    gdb_observers::user_selected_context_changed.notify (USER_SELECTED_FRAME);
 }
 
 /* The "frame" command.  With no argument, print the selected frame
@@ -2290,7 +2290,7 @@  frame_command (char *level_exp, int from_tty)
 
   select_frame (parse_frame_specification (level_exp, NULL));
   if (get_selected_frame_if_set () != prev_frame)
-    observer_notify_user_selected_context_changed (USER_SELECTED_FRAME);
+    gdb_observers::user_selected_context_changed.notify (USER_SELECTED_FRAME);
   else
     print_selected_thread_frame (current_uiout, USER_SELECTED_FRAME);
 }
@@ -2323,7 +2323,7 @@  static void
 up_command (char *count_exp, int from_tty)
 {
   up_silently_base (count_exp);
-  observer_notify_user_selected_context_changed (USER_SELECTED_FRAME);
+  gdb_observers::user_selected_context_changed.notify (USER_SELECTED_FRAME);
 }
 
 /* Select the frame down one or COUNT_EXP stack levels from the previously
@@ -2362,7 +2362,7 @@  static void
 down_command (char *count_exp, int from_tty)
 {
   down_silently_base (count_exp);
-  observer_notify_user_selected_context_changed (USER_SELECTED_FRAME);
+  gdb_observers::user_selected_context_changed.notify (USER_SELECTED_FRAME);
 }
 
 void
diff --git a/gdb/symfile-mem.c b/gdb/symfile-mem.c
index 4ce315d35e..7e255793e3 100644
--- a/gdb/symfile-mem.c
+++ b/gdb/symfile-mem.c
@@ -229,5 +229,5 @@  _initialize_symfile_mem (void)
 
   /* Want to know of each new inferior so that its vsyscall info can
      be extracted.  */
-  observer_attach_inferior_created (add_vsyscall_page);
+  gdb_observers::inferior_created.attach (add_vsyscall_page);
 }
diff --git a/gdb/symfile.c b/gdb/symfile.c
index 9afd9943d9..5472b9c2db 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -1208,13 +1208,13 @@  symbol_file_add_with_addrs (bfd *abfd, const char *name,
 
   if (objfile->sf == NULL)
     {
-      observer_notify_new_objfile (objfile);
+      gdb_observers::new_objfile.notify (objfile);
       return objfile;	/* No symbols.  */
     }
 
   finish_new_objfile (objfile, add_flags);
 
-  observer_notify_new_objfile (objfile);
+  gdb_observers::new_objfile.notify (objfile);
 
   bfd_cache_close_all ();
   return (objfile);
@@ -2621,14 +2621,14 @@  reread_symbols (void)
       clear_symtab_users (0);
 
       /* clear_objfile_data for each objfile was called before freeing it and
-	 observer_notify_new_objfile (NULL) has been called by
+	 gdb_observers::new_objfile.notify (NULL) has been called by
 	 clear_symtab_users above.  Notify the new files now.  */
       for (auto iter : new_objfiles)
-	observer_notify_new_objfile (iter);
+	gdb_observers::new_objfile.notify (objfile);
 
       /* At least one objfile has changed, so we can consider that
          the executable we're debugging has changed too.  */
-      observer_notify_executable_changed ();
+      gdb_observers::executable_changed.notify ();
     }
 }
 
@@ -2864,7 +2864,7 @@  clear_symtab_users (symfile_add_flags add_flags)
   clear_displays ();
   clear_last_displayed_sal ();
   clear_pc_function_cache ();
-  observer_notify_new_objfile (NULL);
+  gdb_observers::new_objfile.notify (NULL);
 
   /* Clear globals which might have pointed into a removed objfile.
      FIXME: It's not clear which of these are supposed to persist
@@ -3873,7 +3873,7 @@  _initialize_symfile (void)
 {
   struct cmd_list_element *c;
 
-  observer_attach_free_objfile (symfile_free_objfile);
+  gdb_observers::free_objfile.attach (symfile_free_objfile);
 
   c = add_cmd ("symbol-file", class_files, symbol_file_command, _("\
 Load symbol table from executable file FILE.\n\
diff --git a/gdb/symtab.c b/gdb/symtab.c
index db705901ca..c701a56c63 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -5819,7 +5819,7 @@  If zero then the symbol cache is disabled."),
 	   _("Flush the symbol cache for each program space."),
 	   &maintenancelist);
 
-  observer_attach_executable_changed (symtab_observer_executable_changed);
-  observer_attach_new_objfile (symtab_new_objfile_observer);
-  observer_attach_free_objfile (symtab_free_objfile_observer);
+  gdb_observers::executable_changed.attach (symtab_observer_executable_changed);
+  gdb_observers::new_objfile.attach (symtab_new_objfile_observer);
+  gdb_observers::free_objfile.attach (symtab_free_objfile_observer);
 }
diff --git a/gdb/testsuite/gdb.gdb/observer.exp b/gdb/testsuite/gdb.gdb/observer.exp
deleted file mode 100644
index a95cab878f..0000000000
--- a/gdb/testsuite/gdb.gdb/observer.exp
+++ /dev/null
@@ -1,143 +0,0 @@ 
-# Copyright 2003-2017 Free Software Foundation, Inc.
-
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-# This file was written by Joel Brobecker (brobecker@gnat.com), derived
-# from xfullpath.exp.
-
-load_lib selftest-support.exp
-
-proc attach_first_observer { message } {
-    gdb_test_no_output "set \$first_obs = observer_attach_test_notification (&observer_test_first_notification_function)" \
-	"$message; attach first observer"
-}
-
-proc attach_second_observer { message } {
-    gdb_test_no_output "set \$second_obs = observer_attach_test_notification (&observer_test_second_notification_function)" \
-	"$message; attach second observer"
-}
-
-proc attach_third_observer { message } {
-    gdb_test_no_output "set \$third_obs = observer_attach_test_notification (&observer_test_third_notification_function)" \
-	"$message; attach third observer"
-}
-
-proc detach_first_observer { message } {
-    gdb_test_no_output "call observer_detach_test_notification (\$first_obs)" \
-	"$message; detach first observer"
-}
-
-proc detach_second_observer { message } {
-    gdb_test_no_output "call observer_detach_test_notification (\$second_obs)" \
-	"$message; detach second observer"
-}
-
-proc detach_third_observer { message } {
-    gdb_test_no_output "call observer_detach_test_notification (\$third_obs)" \
-	"$message; detach third observer"
-}
-
-proc check_counters { first second third message } {
-    gdb_test "print observer_test_first_observer" \
-	".\[0-9\]+ =.*$first" \
-	"$message; check first observer counter value"
-    gdb_test "print observer_test_second_observer" \
-	".\[0-9\]+ =.*$second" \
-	"$message; check second observer counter value"
-    gdb_test "print observer_test_third_observer" \
-	".\[0-9\]+ =.*$third" \
-	"$message; check third observer counter value"
-}
-
-proc reset_counters { message } {
-    gdb_test_no_output "set variable observer_test_first_observer = 0" \
-	"$message; reset first observer counter"
-    gdb_test_no_output "set variable observer_test_second_observer = 0" \
-	"$message; reset second observer counter"
-    gdb_test_no_output "set variable observer_test_third_observer = 0" \
-	"$message; reset third observer counter"
-}
-
-proc test_notifications { first second third message args } {
-    # Do any initialization
-    for {set i 0} {$i < [llength $args]} {incr i} {
-	[lindex $args $i] $message
-    }
-    reset_counters $message
-    # Call observer_notify_test_notification.  Note that this procedure
-    # takes one argument, but this argument is ignored by the observer
-    # callbacks we have installed.  So we just pass an arbitrary value.
-    gdb_test_no_output "call observer_notify_test_notification (0)" \
-	"$message; sending notification"
-    check_counters $first $second $third $message
-}
-
-proc test_observer {} {
-    # First, try sending a notification without any observer attached.
-    test_notifications 0 0 0 "no observer attached"
-
-    # Now, attach one observer, and send a notification.
-    test_notifications 0 1 0 "second observer attached" \
-	attach_second_observer
-
-    # Remove the observer, and send a notification.
-    test_notifications 0 0 0 "second observer detached" \
-	detach_second_observer
-
-    # With a new observer.
-    test_notifications 1 0 0 "1st observer added" \
-	attach_first_observer
-
-    # With 2 observers.
-    test_notifications 1 1 0 "2nd observer added" \
-	attach_second_observer
-
-    # With 3 observers.
-    test_notifications 1 1 1 "3rd observer added" \
-	attach_third_observer
-
-    # Remove middle observer.
-    test_notifications 1 0 1 "2nd observer removed" \
-	detach_second_observer
-
-    # Remove first observer.
-    test_notifications 0 0 1 "1st observer removed" \
-	detach_first_observer
-
-    # Remove last observer.
-    test_notifications 0 0 0 "3rd observer removed" \
-	detach_third_observer
-
-    # Go back to 3 observers, and remove them in a different order...
-    test_notifications 1 1 1 "three observers added" \
-	attach_first_observer \
-	attach_second_observer \
-	attach_third_observer 
-
-    # Remove the third observer.
-    test_notifications 1 1 0 "third observer removed" \
-	detach_third_observer
-
-    # Remove the second observer.
-    test_notifications 1 0 0 "second observer removed" \
-	detach_second_observer
-
-    # Remove the first observer, no more observers.
-    test_notifications 0 0 0 "first observer removed" \
-	detach_first_observer
-
-    return 0
-}
-
-do_self_tests captured_main test_observer
diff --git a/gdb/thread.c b/gdb/thread.c
index f614097926..c395eda9d7 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -209,7 +209,7 @@  set_thread_exited (thread_info *tp, int silent)
 
   if (tp->state != THREAD_EXITED)
     {
-      observer_notify_thread_exit (tp, silent);
+      gdb_observers::thread_exit.notify (tp, silent);
 
       /* Tag it as exited.  */
       tp->state = THREAD_EXITED;
@@ -301,7 +301,7 @@  add_thread_silent (ptid_t ptid)
 	  tp->state = THREAD_STOPPED;
 	  switch_to_thread (ptid);
 
-	  observer_notify_new_thread (tp);
+	  gdb_observers::new_thread.notify (tp);
 
 	  /* All done.  */
 	  return tp;
@@ -312,7 +312,7 @@  add_thread_silent (ptid_t ptid)
     }
 
   tp = new_thread (inf, ptid);
-  observer_notify_new_thread (tp);
+  gdb_observers::new_thread.notify (tp);
 
   return tp;
 }
@@ -874,7 +874,7 @@  thread_change_ptid (ptid_t old_ptid, ptid_t new_ptid)
   tp = find_thread_ptid (old_ptid);
   tp->ptid = new_ptid;
 
-  observer_notify_thread_ptid_changed (old_ptid, new_ptid);
+  gdb_observers::thread_ptid_changed.notify (old_ptid, new_ptid);
 }
 
 /* See gdbthread.h.  */
@@ -954,7 +954,7 @@  set_running (ptid_t ptid, int running)
 	any_started = 1;
     }
   if (any_started)
-    observer_notify_target_resumed (ptid);
+    gdb_observers::target_resumed.notify (ptid);
 }
 
 static int
@@ -1053,7 +1053,7 @@  set_stop_requested (ptid_t ptid, int stop)
   /* Call the stop requested observer so other components of GDB can
      react to this request.  */
   if (stop)
-    observer_notify_thread_stop_requested (ptid);
+    gdb_observers::thread_stop_requested.notify (ptid);
 }
 
 void
@@ -1090,7 +1090,7 @@  finish_thread_state (ptid_t ptid)
     }
 
   if (any_started)
-    observer_notify_target_resumed (ptid);
+    gdb_observers::target_resumed.notify (ptid);
 }
 
 void
@@ -1852,8 +1852,8 @@  thread_command (const char *tidstr, int from_tty)
 	}
       else
 	{
-	  observer_notify_user_selected_context_changed (USER_SELECTED_THREAD
-							 | USER_SELECTED_FRAME);
+	  gdb_observers::user_selected_context_changed.notify
+	    (USER_SELECTED_THREAD | USER_SELECTED_FRAME);
 	}
     }
 }
diff --git a/gdb/top.c b/gdb/top.c
index 9f5dd58d21..b6de000923 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -1909,7 +1909,7 @@  static void
 set_gdb_datadir (char *args, int from_tty, struct cmd_list_element *c)
 {
   set_gdb_data_directory (staged_gdb_datadir);
-  observer_notify_gdb_datadir_changed ();
+  gdb_observers::gdb_datadir_changed.notify ();
 }
 
 /* "show" command for the gdb_datadir configuration variable.  */
diff --git a/gdb/tracepoint.c b/gdb/tracepoint.c
index 78f4c86126..df5b308913 100644
--- a/gdb/tracepoint.c
+++ b/gdb/tracepoint.c
@@ -315,7 +315,7 @@  delete_trace_state_variable (const char *name)
   for (ix = 0; VEC_iterate (tsv_s, tvariables, ix, tsv); ++ix)
     if (strcmp (name, tsv->name) == 0)
       {
-	observer_notify_tsv_deleted (tsv);
+	gdb_observers::tsv_deleted.notify (tsv);
 
 	xfree ((void *)tsv->name);
 	VEC_unordered_remove (tsv_s, tvariables, ix);
@@ -390,7 +390,7 @@  trace_variable_command (char *args, int from_tty)
       if (tsv->initial_value != initval)
 	{
 	  tsv->initial_value = initval;
-	  observer_notify_tsv_modified (tsv);
+	  gdb_observers::tsv_modified.notify (tsv);
 	}
       printf_filtered (_("Trace state variable $%s "
 			 "now has initial value %s.\n"),
@@ -402,7 +402,7 @@  trace_variable_command (char *args, int from_tty)
   tsv = create_trace_state_variable (name.c_str ());
   tsv->initial_value = initval;
 
-  observer_notify_tsv_created (tsv);
+  gdb_observers::tsv_created.notify (tsv);
 
   printf_filtered (_("Trace state variable $%s "
 		     "created, with initial value %s.\n"),
@@ -417,7 +417,7 @@  delete_trace_variable_command (const char *args, int from_tty)
       if (query (_("Delete all trace state variables? ")))
 	VEC_free (tsv_s, tvariables);
       dont_repeat ();
-      observer_notify_tsv_deleted (NULL);
+      gdb_observers::tsv_deleted.notify (NULL);
       return;
     }
 
@@ -1679,7 +1679,7 @@  start_tracing (char *notes)
 						 loc->gdbarch);
 
       if (bp_location_downloaded)
-	observer_notify_breakpoint_modified (b);
+	gdb_observers::breakpoint_modified.notify (b);
     }
   VEC_free (breakpoint_p, tp_vec);
 
@@ -2197,7 +2197,7 @@  tfind_1 (enum trace_find_type type, int num,
   set_tracepoint_num (tp ? tp->number : target_tracept);
 
   if (target_frameno != get_traceframe_number ())
-    observer_notify_traceframe_changed (target_frameno, tracepoint_number);
+    gdb_observers::traceframe_changed.notify (target_frameno, tracepoint_number);
 
   set_current_traceframe (target_frameno);
 
@@ -3262,7 +3262,7 @@  merge_uploaded_tracepoints (struct uploaded_tp **uploaded_tps)
   /* Notify 'breakpoint-modified' observer that at least one of B's
      locations was changed.  */
   for (ix = 0; VEC_iterate (breakpoint_p, modified_tp, ix, b); ix++)
-    observer_notify_breakpoint_modified (b);
+    gdb_observers::breakpoint_modified.notify (b);
 
   VEC_free (breakpoint_p, modified_tp);
   free_uploaded_tps (uploaded_tps);
@@ -3310,7 +3310,7 @@  create_tsv_from_upload (struct uploaded_tsv *utsv)
   tsv->initial_value = utsv->initial_value;
   tsv->builtin = utsv->builtin;
 
-  observer_notify_tsv_created (tsv);
+  gdb_observers::tsv_created.notify (tsv);
 
   return tsv;
 }
diff --git a/gdb/tui/tui-hooks.c b/gdb/tui/tui-hooks.c
index 2dd1bc02d0..22ce927d71 100644
--- a/gdb/tui/tui-hooks.c
+++ b/gdb/tui/tui-hooks.c
@@ -204,13 +204,20 @@  tui_normal_stop (struct bpstats *bs, int print_frame)
 }
 
 /* Observers created when installing TUI hooks.  */
-static struct observer *tui_bp_created_observer;
-static struct observer *tui_bp_deleted_observer;
-static struct observer *tui_bp_modified_observer;
-static struct observer *tui_inferior_exit_observer;
-static struct observer *tui_before_prompt_observer;
-static struct observer *tui_normal_stop_observer;
-static struct observer *tui_register_changed_observer;
+static gdb_observers::observer<struct breakpoint *>::token_type
+  tui_bp_created_observer;
+static gdb_observers::observer<struct breakpoint *>::token_type
+  tui_bp_deleted_observer;
+static gdb_observers::observer<struct breakpoint *>::token_type
+  tui_bp_modified_observer;
+static gdb_observers::observer<struct inferior *>::token_type
+  tui_inferior_exit_observer;
+static gdb_observers::observer<const char *>::token_type
+  tui_before_prompt_observer;
+static gdb_observers::observer<struct bpstats *, int>::token_type
+  tui_normal_stop_observer;
+static gdb_observers::observer<struct frame_info *, int>::token_type
+  tui_register_changed_observer;
 
 /* Install the TUI specific hooks.  */
 void
@@ -225,19 +232,19 @@  tui_install_hooks (void)
 
   /* Install the event hooks.  */
   tui_bp_created_observer
-    = observer_attach_breakpoint_created (tui_event_create_breakpoint);
+    = gdb_observers::breakpoint_created.attach (tui_event_create_breakpoint);
   tui_bp_deleted_observer
-    = observer_attach_breakpoint_deleted (tui_event_delete_breakpoint);
+    = gdb_observers::breakpoint_deleted.attach (tui_event_delete_breakpoint);
   tui_bp_modified_observer
-    = observer_attach_breakpoint_modified (tui_event_modify_breakpoint);
+    = gdb_observers::breakpoint_modified.attach (tui_event_modify_breakpoint);
   tui_inferior_exit_observer
-    = observer_attach_inferior_exit (tui_inferior_exit);
+    = gdb_observers::inferior_exit.attach (tui_inferior_exit);
   tui_before_prompt_observer
-    = observer_attach_before_prompt (tui_before_prompt);
+    = gdb_observers::before_prompt.attach (tui_before_prompt);
   tui_normal_stop_observer
-    = observer_attach_normal_stop (tui_normal_stop);
+    = gdb_observers::normal_stop.attach (tui_normal_stop);
   tui_register_changed_observer
-    = observer_attach_register_changed (tui_register_changed);
+    = gdb_observers::register_changed.attach (tui_register_changed);
 }
 
 /* Remove the TUI specific hooks.  */
@@ -247,25 +254,25 @@  tui_remove_hooks (void)
   deprecated_print_frame_info_listing_hook = 0;
   deprecated_query_hook = 0;
   /* Remove our observers.  */
-  observer_detach_breakpoint_created (tui_bp_created_observer);
-  tui_bp_created_observer = NULL;
-  observer_detach_breakpoint_deleted (tui_bp_deleted_observer);
-  tui_bp_deleted_observer = NULL;
-  observer_detach_breakpoint_modified (tui_bp_modified_observer);
-  tui_bp_modified_observer = NULL;
-  observer_detach_inferior_exit (tui_inferior_exit_observer);
-  tui_inferior_exit_observer = NULL;
-  observer_detach_before_prompt (tui_before_prompt_observer);
-  tui_before_prompt_observer = NULL;
-  observer_detach_normal_stop (tui_normal_stop_observer);
-  tui_normal_stop_observer = NULL;
-  observer_detach_register_changed (tui_register_changed_observer);
-  tui_register_changed_observer = NULL;
+  gdb_observers::breakpoint_created.detach (tui_bp_created_observer);
+  tui_bp_created_observer = gdb_observers::breakpoint_created.null_token;
+  gdb_observers::breakpoint_deleted.detach (tui_bp_deleted_observer);
+  tui_bp_deleted_observer = gdb_observers::breakpoint_deleted.null_token;
+  gdb_observers::breakpoint_modified.detach (tui_bp_modified_observer);
+  tui_bp_modified_observer = gdb_observers::breakpoint_modified.null_token;
+  gdb_observers::inferior_exit.detach (tui_inferior_exit_observer);
+  tui_inferior_exit_observer = gdb_observers::inferior_exit.null_token;
+  gdb_observers::before_prompt.detach (tui_before_prompt_observer);
+  tui_before_prompt_observer = gdb_observers::before_prompt.null_token;
+  gdb_observers::normal_stop.detach (tui_normal_stop_observer);
+  tui_normal_stop_observer = gdb_observers::normal_stop.null_token;
+  gdb_observers::register_changed.detach (tui_register_changed_observer);
+  tui_register_changed_observer = gdb_observers::register_changed.null_token;
 }
 
 void
 _initialize_tui_hooks (void)
 {
   /* Install the permanent hooks.  */
-  observer_attach_new_objfile (tui_new_objfile_hook);
+  gdb_observers::new_objfile.attach (tui_new_objfile_hook);
 }
diff --git a/gdb/tui/tui-interp.c b/gdb/tui/tui-interp.c
index e5e73210c7..e2f266afef 100644
--- a/gdb/tui/tui-interp.c
+++ b/gdb/tui/tui-interp.c
@@ -326,14 +326,14 @@  _initialize_tui_interp (void)
     }
 
   /* If changing this, remember to update cli-interp.c as well.  */
-  observer_attach_normal_stop (tui_on_normal_stop);
-  observer_attach_signal_received (tui_on_signal_received);
-  observer_attach_end_stepping_range (tui_on_end_stepping_range);
-  observer_attach_signal_exited (tui_on_signal_exited);
-  observer_attach_exited (tui_on_exited);
-  observer_attach_no_history (tui_on_no_history);
-  observer_attach_sync_execution_done (tui_on_sync_execution_done);
-  observer_attach_command_error (tui_on_command_error);
-  observer_attach_user_selected_context_changed
+  gdb_observers::normal_stop.attach (tui_on_normal_stop);
+  gdb_observers::signal_received.attach (tui_on_signal_received);
+  gdb_observers::end_stepping_range.attach (tui_on_end_stepping_range);
+  gdb_observers::signal_exited.attach (tui_on_signal_exited);
+  gdb_observers::exited.attach (tui_on_exited);
+  gdb_observers::no_history.attach (tui_on_no_history);
+  gdb_observers::sync_execution_done.attach (tui_on_sync_execution_done);
+  gdb_observers::command_error.attach (tui_on_command_error);
+  gdb_observers::user_selected_context_changed.attach
     (tui_on_user_selected_context_changed);
 }
diff --git a/gdb/valops.c b/gdb/valops.c
index de4544cd29..8f6a78a50b 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -1196,7 +1196,7 @@  value_assign (struct value *toval, struct value *fromval)
 	      }
 	  }
 
-	observer_notify_register_changed (frame, value_reg);
+	gdb_observers::register_changed.notify (frame, value_reg);
 	break;
       }
 
@@ -1227,7 +1227,7 @@  value_assign (struct value *toval, struct value *fromval)
     case lval_register:
     case lval_computed:
 
-      observer_notify_target_changed (&current_target);
+      gdb_observers::target_changed.notify (&current_target);
 
       /* Having destroyed the frame cache, restore the selected
 	 frame.  */