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Re: How to debug modification to a variable value?
From: |
alin.s |
Subject: |
Re: How to debug modification to a variable value? |
Date: |
Tue, 26 Jan 2010 07:52:23 -0800 (PST) |
I suggest you to use the WATCH in gdb for modifications of the variable,
AWATCH for reading of the variable, etc.
To detect the location of the variable is easy: install a breakpoint in
make-variable-buffer-local that stops when exactly the variable you are
interested about is set, then see there the location of tg-schema-alist.
Afterward you can use the x* functions from .gdbinit of emacs to debug your
problem...
Tassilo Horn-5 wrote:
>
> Hi all,
>
> today I had some strange problems with a major mode we use at my
> institute, and that I created and maintain. This mode defines some
> buffer-local variable:
>
> --8<---------------cut here---------------start------------->8---
> (defvar tg-schema-alist nil
> "The schema of the current TG file.")
> (make-variable-buffer-local 'tg-schema-alist)
> --8<---------------cut here---------------end--------------->8---
>
> This variable is set once, when a new graph is loaded (whatever that
> means, but there is only one function that setqs the variable).
>
> Also, there's a function, which refreshes some font-locking stuff when
> saving. This function is added to `after-save-hook' locally.
>
> --8<---------------cut here---------------start------------->8---
> after-save-hook is a variable defined in `files.el'.
> Its value is
> (t greql-set-fontlock-types-regex)
>
> Local in buffer method-calls-per-activity.greql; global value is nil
> --8<---------------cut here---------------end--------------->8---
>
> Now, my problem was that under some circumstances after saving, the
> buffer-local value of `tg-schema-alist' was gone, i.e. set to nil.
>
> I double-checked `greql-set-fontlock-types-regex' that it doesn't modify
> `tg-schema-alist', and it doesn't. I also removed all destructive
> function calls in there, although it operates only on a list created by
> `mapcar', and that's a copy anyway, right?
>
> Till now, I couldn't reproduce this behavior. After restarting emacs,
> the problem was gone first. Suddenly, it appeared again. Maybe it has
> something to do with using the same buffer in many frames (tty and X),
> but I cannot tell for sure...
>
> So what I need is some way to be put in the debugger when the value of
> `tg-schema-alist' is modified. Is that feasible? I tried adding an
> after advice to `setq' which does exactly that, but that screwed my
> emacs instance. I guess it's no good idea to advice such primitives...
>
> Bye,
> Tassilo
>
>
>
>
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- Re: How to debug modification to a variable value?, (continued)
- Re: How to debug modification to a variable value?, Stefan Monnier, 2010/01/26
- Re: How to debug modification to a variable value?, alin.s, 2010/01/26
- Re: How to debug modification to a variable value?, Andreas Roehler, 2010/01/27
- Re: How to debug modification to a variable value?, Tassilo Horn, 2010/01/27
- Re: How to debug modification to a variable value?, Andreas Roehler, 2010/01/27
Re: How to debug modification to a variable value?, Davis Herring, 2010/01/25
Re: How to debug modification to a variable value?,
alin.s <=