Refine the 'define' documentation
Checks
Commit Message
A while ago, an AdaCore user reported some difficulties with the
'define' command. While some of these difficulties are intrinsic, or
at least difficult to change, it seemed sensible to document a couple
of the typical problems -- and to make the text describing argument
substitution a bit more prominent.
---
gdb/doc/gdb.texinfo | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
Comments
> From: Tom Tromey <tromey@adacore.com>
> Cc: Tom Tromey <tromey@adacore.com>
> Date: Tue, 23 Jul 2024 10:07:54 -0600
>
> A while ago, an AdaCore user reported some difficulties with the
> 'define' command. While some of these difficulties are intrinsic, or
> at least difficult to change, it seemed sensible to document a couple
> of the typical problems -- and to make the text describing argument
> substitution a bit more prominent.
> ---
> gdb/doc/gdb.texinfo | 22 ++++++++++++++++------
> 1 file changed, 16 insertions(+), 6 deletions(-)
Thanks, this is OK.
Approved-By: Eli Zaretskii <eliz@gnu.org>
@@ -29228,9 +29228,21 @@ files.
@cindex arguments, to user-defined commands
A @dfn{user-defined command} is a sequence of @value{GDBN} commands to
which you assign a new name as a command. This is done with the
-@code{define} command. User commands may accept an unlimited number of arguments
-separated by whitespace. Arguments are accessed within the user command
-via @code{$arg0@dots{}$argN}. A trivial example:
+@code{define} command.
+
+User commands may accept an unlimited number of arguments separated by
+whitespace. Arguments are accessed within the user command via
+@code{$arg0@dots{}$argN}. The arguments are text substitutions, so
+they may reference variables, use complex expressions, or even perform
+inferior functions calls. Note, however, that this textual
+substitution means that working with certain arguments is difficult.
+For example, there is no way for the user to pass an argument
+containing a space; and while stringifying an argument can be done
+using an expression like @code{"$arg1"}, this will fail if the
+argument contains a quote. For more complicated and robust commands,
+we recommend writing them in Python; see @ref{CLI Commands In Python}.
+
+A trivial example:
@smallexample
define adder
@@ -29247,9 +29259,7 @@ adder 1 2 3
@noindent
This defines the command @code{adder}, which prints the sum of
-its three arguments. Note the arguments are text substitutions, so they may
-reference variables, use complex expressions, or even perform inferior
-functions calls.
+its three arguments.
@cindex argument count in user-defined commands
@cindex how many arguments (user-defined commands)