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'

Important settings:
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  value of $LC_TIME: nil
  value of $LANG: ENU
  value of $XMODIFIERS: nil
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