bug#8549: 23.3; Undocumented setting of eval-expression-debug-on-error

bug#8549: 23.3; Undocumented setting of eval-expression-debug-on-error

[Uday S Reddy]

There is a tricky variable called `eval-expression-debug-on-error' which
I didn't notice till recently.

It is getting set automatically in lisp-interaction-mode and in the Lisp
debugger.  The manual doesn't say anywhere that this is being done.

I would prefer that it doesn't get set automatically, given that it has a
tricky behavior.  In the light of my previous bug report #8548 that the
debugger can't exit recursive editing levels, making any kind of typing
mistake while working with the debugger puts it in a recursive editing level
where it gets stuck.

  http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8548

If you don't want to change the lisp-interaction-mode and the debugger-mode,
can you at least document it in the manual that the variable gets set in
these modes so that the users can unset it in the mode-hooks?  I have
suffered for several years needlessly.

(By the way, edebug doesn't seem to set the variable.)

Cheers,
Uday




In GNU Emacs 23.3.1 (i386-mingw-nt5.1.2600)
 of 2011-03-10 on 3249CTO
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.5) --no-opt --cflags -Ic:/imagesupport/include'

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-- 

bug#8549: 23.3; Undocumented setting of eval-expression-debug-on-error

[Lars Magne Ingebrigtsen]

Uday S Reddy <u.s.reddy@cs.bham.ac.uk> writes:

> There is a tricky variable called `eval-expression-debug-on-error' which
> I didn't notice till recently.
>
> It is getting set automatically in lisp-interaction-mode and in the Lisp
> debugger.  The manual doesn't say anywhere that this is being done.
>
> I would prefer that it doesn't get set automatically, given that it has a
> tricky behavior.  In the light of my previous bug report #8548 that the
> debugger can't exit recursive editing levels, making any kind of typing
> mistake while working with the debugger puts it in a recursive editing level
> where it gets stuck.
>
>   http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8548
>
> If you don't want to change the lisp-interaction-mode and the debugger-mode,
> can you at least document it in the manual that the variable gets set in
> these modes so that the users can unset it in the mode-hooks?  I have
> suffered for several years needlessly.

I've now mentioned this in the manual, but I've been trying to grep
through the code and see why/where this is done, and I'm coming up
empty.

Does anybody know?  And is this a feature or a bug?
`eval-expression-debug-on-error' doesn't sound like something that
should affect `M-x debug', and the other `eval-expression-' variables
are not heeded by doing `M-x debug'.  So it seems inconsistent and
somewhat confusing.

-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/

bug#8549: 23.3; Undocumented setting of eval-expression-debug-on-error

[Uday S Reddy]

Dear Lars, thanks for your help with Emacs bugs!  In response to my other
related bug report, #8548, Stefan said that "this part of the C code was
changed recently".  I haven't checked the development version yet.  I will
do so now.

Cheers,
Uday

bug#8549: 23.3; Undocumented setting of eval-expression-debug-on-error

[Uday S Reddy]

Ok, Checked the development branch as of 2011-06-13.  The variable
`eval-expression-debug-on-error' continues to get set.

On the other hand, exit-recursive-edit is working from the recursive
debugger entry.  So the bug report #8548 can be closed.

Cheers,
Uday

bug#8549: 23.3; Undocumented setting of eval-expression-debug-on-error

[npostavs]

tags 8549 fixed
close 8549
quit

Uday S Reddy <u.s.reddy@cs.bham.ac.uk> writes:

> Ok, Checked the development branch as of 2011-06-13.  The variable
> `eval-expression-debug-on-error' continues to get set.

I don't understand what is meant by the variable getting "set".  Its
default value is t, and has been since it was first introduced in
b49df39d (1999-09-14 "(eval-expression-print-level): New variable....").

It was added to the manual in 66249842 (2011-07-15 "(Using Debugger):
Mention @code{eval-expression-debug-on-error}") which says it fixes this
bug, so I'm closing it now.