Re: Customize buttons that changeuser'scustomfileshouldaskforconfirmation

[Luc Teirlinck]

To try to be more clear:

Lennart Borgman wrote:
   
   Or did I misunderstand that? (setq custom-file "Y") together with
   the common use of (load custom-file) gives at least me a feeling that many
   would expect "get saved" to read from Y.

I suggested to set:

(setq custom-file "Y")
(load custom-file)

_in your .emacs_.

But here we are discussing what happens if you change custom-file in
an already running Emacs session, after a custom-file has already been
loaded.  In that situation loading that _second_ Custom file (which
presumably is an empty file to be written into by the current Emacs)
does not make a lot of sense.  The main type of situation in which one
might actually want to change custom-file in a running Emacs is the
following.

Suppose you are using Emacs 21.4 and Emacs 22 comes out.

You now start 21.4 and set custom-file _using Custom_ (important) to
".emacs-custom-22.1.el" or similar.  If I remember well (I have
actually done such things, but a while ago) that file does _not_ need
to exist.  Now all your 21.4 customizations are copied in the newly
created 22.1 custom file, except for `custom-file', which gets
correctly updated.  You then write code in your .emacs to load
".emacs-custom-22.1.el" if the Emacs version is 22.1.  You start 22.1
and watch out for possible errors due to incompatibilities with 21.4.
Then you do M-x customize-changed RET 21.4.

   But it is actually not defined now of course.

Currently, Custom stores the SAVED value in the saved-value property.
The resulting behavior seems OK to me.

Sincerely,

Luc.