From: Skip Montanaro <skip.montanaro@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: Help GNU Emacs <help-gnu-emacs@gnu.org>
Subject: Re: Executing Emacs commands when a gdb breakpoint is hit
Date: Wed, 22 Jan 2020 07:48:17 -0600 [thread overview]
Message-ID: <CANc-5UziODCMhvwq8poxqmpFLNQ-gmKq3VemJg1WUP-jAzh1Qw@mail.gmail.com> (raw)
In-Reply-To: <83o8uwvekv.fsf@gnu.org>
>
> Upgrade to a newer Emacs. This problem was fixed in Emacs 26.2. A
> workaround is to use "commands" instead of its short form "comm".
>
Thanks. That's taken care of. Now, is it possible to trigger an Emacs Lisp
function of some sort when a GDB breakpoint is hit? I see the
gdb-stopped-functions variable. This simple function seems to execute when
my compiler_set_lineno breakpoint is hit:
(defun stopped (reason)
(message "%s" reason))
(setq gdb-stopped-functions '(stopped))
I worked out a more complex stopped function which was supposed to get the
filename and current line number of the Python file being compiled. I was
able to execute the bits interactively to get the values I needed.
Unfortunately, the function is called before *gud-python* has a prompt
(it's not really ready for input). This is the key function which plucks
expression values from the *gud-python* session:
(defun get-gdb-value (expr)
"evaluate EXPR in *gud-python* buffer and return as a string"
(with-current-buffer "*gud-python*"
(save-excursion
(goto-char (point-max))
(insert (concat "print " expr))
(comint-send-input)
(goto-char (point-max))
(forward-line -1)
(move-beginning-of-line nil)
(search-forward " = '")
(push-mark)
(search-forward "'")
(backward-char 1)
(buffer-substring-no-properties (mark) (point))
(pop-mark))))
It's called from my registered stop function like so:
...
(let ((fname (get-gdb-value "c->c_filename"))
(lineno (string-to-number (get-gdb-value "c->u->u_lineno")))
...
I tried sticking in a short sleep, but that didn't help. Is there a way to
force the *gud-python* to be ready for user input before calling
get-gdb-value?
Thanks,
Skip
next prev parent reply other threads:[~2020-01-22 13:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-21 18:02 Executing Emacs commands when a gdb breakpoint is hit Skip Montanaro
2020-01-21 18:39 ` Eli Zaretskii
2020-01-22 13:48 ` Skip Montanaro [this message]
2020-01-22 17:04 ` Eli Zaretskii
2020-01-22 19:55 ` otadmor .
2020-01-22 21:07 ` Skip Montanaro
2020-01-23 14:45 ` Eli Zaretskii
2020-01-23 21:00 ` Skip Montanaro
2020-01-24 8:01 ` Eli Zaretskii
2020-04-07 20:21 ` otadmor .
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