Re: How to debug strange value changes of a variable?

[Alex Kost]

Marcin Borkowski (2015-01-01 03:23 +0300) wrote:

> On 2014-12-31, at 22:09, Michael Heerdegen <michael_heerdegen@web.de> wrote:

[...]

>> Also note that changing a buffer's major mode removes all buffer local
>> bindings in the current buffer.  That could maybe happen in your case.
>
> Thank you, thank you, thank you, thank you so much!  I'd *never* think
> of that (I didn't even know that).  That was it!  The first time my
> function was called, the buffer was in fundamental mode; all subsequent
> times, it was in mu4e-compose-mode.  That should explain everything.
>
> Now the question is: what to do.  I could dive into mu4e sources (which
> I'm just a bit too lazy to do now).  I could just start
> mu4e-compose-mode myself in my function and see what happens (I'll try
> that).  Other than that, I don't have many ideas.

[...]

I didn't follow the thread but IIUC you want your variable to survive a
changing of a major-mode.  If so, you can do it using 'permanent-local'
property:

  (put '<your-var> 'permanent-local t)

See (info "(elisp) Creating Buffer-Local").

-- 
Alex