Subject: bug#21529: 2015-09-20; Xemacs, auctex git, cannot run latex,pdflatexx

From: Tassilo Horn <[email-masked]>
Date: Tue, 22 Sep 2015 08:37:03 +0200

Uwe Brauer <[email-masked]> writes:

>    > This entry is there by default, you must have set
>    > `TeX-expand-list' somewhere.
>
> I think what happens is this: I have TeX-expand-list customized and
> emacs copies all its values into, in my case, custom-init.el and saves
> the changes I did. So if a new variable is added to that list it seems
> that the list in custom-init.el «blocks» the new feature. At least for
> Xemacs why this does not happen in GNU I do not know.

I think it's the same there.  The customization facility sets variables,
thus it is simply not really good for variables whose default value is a
non-empty list.  I think we could use a :set property function to handle
these situation where the function wouldn't actually set the value but
just add to it, e.g., using `push' or `pushnew'.  But then the problem
would be that the user wouldn't have a chance to remove entries from
such variables.  Well, in the case of `TeX-expand-list' he could add
do-nothing entries to override the default ones, I guess.

Another approach with the same limitations would be that we add a
variable `TeX-expand-list-builtin' with all the current default
expansions and leave `TeX-expand-list' to the user.

I think we should probably do the latter because we use that approach
for several other variables already.

Bye,
Tassilo