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Re: Problems with debug-on-entry in the Lisp debugger.
From: |
Lute Kamstra |
Subject: |
Re: Problems with debug-on-entry in the Lisp debugger. |
Date: |
Mon, 07 Mar 2005 16:20:55 +0100 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (gnu/linux) |
Stefan Monnier <address@hidden> writes:
>> I can think of two points in a macro to set a break for the
>> debugger: just before macro expansion and just after it, right
>> before the evaluation of the resulting sexp. In both cases,
>> hiding the debug-on-entry code from the user of the debugger
>> seems not possible.
>
> To me "entry of a macro" is very clearly "just before expansion".
> Especially if you think of macro-expansion occurring because of
> explicit calls to macroexpand (e.g. in the byte-compiler) rather
> than as a direct part of interpretation.
I see you implemented this. This makes debug-on-entry for macros a
lot better, of course. Thanks. But the problem I mentioned remains:
the debug-entry-code is visible. For example:
(defmacro inc (var)
(list 'setq var (list '1+ var)))
(debug-on-entry 'inc)
(progn (setq x 0) (inc x))
gives a backtrace like this:
------ Buffer: *Backtrace* ------
Debugger entered--entering a function:
* (lambda (var) (if (or inhibit-debug-on-entry debugger-jumping-flag) nil
(debug ...)) (list (quote setq) var (list ... var)))(x)
(inc x)
(progn (setq x 0) (inc x))
eval((progn (setq x 0) (inc x)))
eval-last-sexp-1(nil)
eval-last-sexp(nil)
call-interactively(eval-last-sexp)
------ Buffer: *Backtrace* ------
>> Shall I go ahead and try to implement this, or do people think this
>> is a bad idea?
>
> I think it's a bad idea. The interpreter is already way too slow,
> I'd rather not make it worse.
I think the effect on performance will be very minimal. Do you know
of a good way to test the performance of the interpreter so that I can
measure the impact of my proposed change? Can you indicate how much
performance loss would be acceptable for you?
Lute.
Re: Problems with debug-on-entry in the Lisp debugger., Kim F. Storm, 2005/03/07
Re: Problems with debug-on-entry in the Lisp debugger., Richard Stallman, 2005/03/07