Test the interaction between GDBHISTSIZE and .gdbinit
Commit Message
On Thu, Jun 18, 2015 at 8:44 AM, Patrick Palka <patrick@parcs.ath.cx> wrote:
> On Thu, Jun 18, 2015 at 5:06 AM, Pedro Alves <palves@redhat.com> wrote:
>> On 06/17/2015 09:17 PM, Patrick Palka wrote:
>>> The value inside the GDBHISTSIZE environment variable, only if valid,
>>> should override setting the history size through one's .gdbinit file.
>>
>> Thanks, looks good.
>>
>>> + unset -nocomplain env(GDBHISTSIZE)
>>> array set env [array get old_env]
>>
>> Though this unset looks unnecessary, given that the following line
>> restores the whole array.
>
> It turns out that
>
> array set env [array get old_env]
>
> does not completely restore the env array to its original state. What
> it seems to do is to reset each pre-existing environment variable
> (existing in the saved env array) to its original value. New
> environment variables that were set inside the env array in the
> meantime do not get unset after restoring. So e.g. after doing
>
> array set old_env [array get env]
> set env(SOME_NEW_VAR) foo
> array set env [array get old_env]
>
> the environment variable SOME_NEW_VAR=foo will still be in the env
> array. So this "array set env" trick is insufficient. That is why
> the unset of GDBHISTSIZE is necessary there.
>
> To make the pattern of "temporarily altering global variables,
> restoring their original value afterwards" more convenient and less
> error-prone, I've been thinking about introducing a new tcl proc that
> acts as a wrapper for saving/restoring a specified list of variables.
> Its use would look something like:
>
> save_vars { INTERNAL_GDBFLAGS env(GDBHISTSIZE) env(HOME) } {
> append INTERNAL_GDBFLAGS " -nx"
> unset -nocomplain env(GDBHISTSIZE)
> unset -nocomplain env(HOME)
> gdb_test ....
> more_gdb_test ...
> }
>
> which guarantees that after the body has finished executing, the given
> list of variables will have their contents restored to their original
> values. What do you think about this?
Here is an implementation of save_vars (bad name I know) which can
successfully replace the manual saving/restoring of globals done in
gdbinit-history.exp, gdbhistsize-history.exp and readline.exp. (TCL
sure is cool.)
Comments
On 06/18/2015 03:47 PM, Patrick Palka wrote:
> Here is an implementation of save_vars (bad name I know) which can
> successfully replace the manual saving/restoring of globals done in
> gdbinit-history.exp, gdbhistsize-history.exp and readline.exp. (TCL
> sure is cool.)
>
I like it. :-)
Thanks,
Pedro Alves
On Thu, Jun 18, 2015 at 9:47 AM, Patrick Palka <patrick@parcs.ath.cx> wrote:
> Here is an implementation of save_vars (bad name I know) which can
> successfully replace the manual saving/restoring of globals done in
> gdbinit-history.exp, gdbhistsize-history.exp and readline.exp. (TCL
> sure is cool.)
Emacs has save-excursion so there is some precedent for the naming choice.
LGTM
Hi Patrick,
On 06/18/2015 04:29 PM, Pedro Alves wrote:
> On 06/18/2015 03:47 PM, Patrick Palka wrote:
>
>> Here is an implementation of save_vars (bad name I know) which can
>> successfully replace the manual saving/restoring of globals done in
>> gdbinit-history.exp, gdbhistsize-history.exp and readline.exp. (TCL
>> sure is cool.)
>>
>
> I like it. :-)
I just found another use for this. AFAICS, Doug was OK with it
as well.
Mind if we put this in?
Thanks,
Pedro Alves
On Tue, Aug 11, 2015 at 6:11 PM, Pedro Alves <palves@redhat.com> wrote:
> Hi Patrick,
>
> On 06/18/2015 04:29 PM, Pedro Alves wrote:
>> On 06/18/2015 03:47 PM, Patrick Palka wrote:
>>
>>> Here is an implementation of save_vars (bad name I know) which can
>>> successfully replace the manual saving/restoring of globals done in
>>> gdbinit-history.exp, gdbhistsize-history.exp and readline.exp. (TCL
>>> sure is cool.)
>>>
>>
>> I like it. :-)
>
> I just found another use for this. AFAICS, Doug was OK with it
> as well.
>
> Mind if we put this in?
Done.
@@ -1830,6 +1830,71 @@ proc with_test_prefix { prefix body } {
}
}
+# Run BODY in the context of the caller. After BODY is run, the variables
+# listed in VARS will be reset to the values they had before BODY was run.
+#
+# This is useful for providing a scope in which it is safe to temporarily
+# modify global variables, e.g.
+#
+# global INTERNAL_GDBFLAGS
+# global env(GDBHISTSIZE)
+#
+# save_vars { INTERNAL_GDBFLAGS env(GDBHISTSIZE) } {
+# append INTERNAL_GDBFLAGS " -nx"
+# unset -nocomplain env(GDBHISTSIZE)
+# gdb_start
+# gdb_test ...
+# }
+#
+# Here, although INTERNAL_GDBFLAGS and env(GDBHISTSIZE) are modified inside the
+# BODY, this proc will guarantee that the modifications will be undone after
+# BODY finishes executing.
+
+proc save_vars { vars body } {
+ array set saved_scalars { }
+ array set saved_arrays { }
+ set unset_vars { }
+
+ foreach var $vars {
+ # First evaluate VAR in the context of the caller in case the variable
+ # name may be a not-yet-interpolated string like env($foo)
+ set var [uplevel 1 list $var]
+
+ if [uplevel 1 [list info exists $var]] {
+ if [uplevel 1 [list array exists $var]] {
+ set saved_arrays($var) [uplevel 1 [list array get $var]]
+ } else {
+ set saved_scalars($var) [uplevel 1 [list set $var]]
+ }
+ } else {
+ lappend unset_vars $var
+ }
+ }
+
+ set code [catch {uplevel 1 $body} result]
+
+ foreach {var value} [array get saved_scalars] {
+ uplevel 1 [list set $var $value]
+ }
+
+ foreach {var value} [array get saved_arrays] {
+ uplevel 1 [list unset $var]
+ uplevel 1 [list array set $var $value]
+ }
+
+ foreach var $unset_vars {
+ uplevel 1 [list unset -nocomplain $var]
+ }
+
+ if {$code == 1} {
+ global errorInfo errorCode
+ return -code $code -errorinfo $errorInfo -errorcode $errorCode $result
+ } else {
+ return -code $code $result
+ }
+}
+
+
# Run tests in BODY with GDB prompt and variable $gdb_prompt set to
# PROMPT. When BODY is finished, restore GDB prompt and variable
# $gdb_prompt.