Re: Customize buttons that change user's custom fileshouldaskforconfirmation

[Luc Teirlinck]

Richard Stallman wrote:

   The concept of "exiting" does not make sense for a Custom buffer, but
   there could be a buffer-wide Activate command, "Put this in effect",
   which combines Set and Save.  If that were the only way to make values
   take effect, it would be a lot simpler than the current Custom
   facility.

   In addition to Activate, there would be Cancel and Standard Values.
   And perhaps What's Changed, which says what would change if you use
   Activate right now.

   What do people think of the idea?

I like the _current_ Custom interface.  I believe that its _general
design_, including the button structure, is hard to improve on.  I
would leave it alone.  Of course, there are various bugs that need to
be fixed and various _details_ that can be improved.

Most of the more serious problems that Custom suffers from, several of
which I have pointed out, result from the fact that Custom makes
certain assumptions for its correct functioning that Emacs does not
adhere to (or does currently not adhere to).

The two main ones are:

1.  The value given in the defcustom is the standard Emacs default
    value as seen in `emacs -q'.

I believe that for this one, we agreed that we would make sure that
Emacs adhered much better to this than it currently does, ideally
completely.  We already started implementing this, although there
still is much to do.

2.  A variable defined by defcustom is reserved for the user.  Code
    never messes with it.  If code needs to add stuff to hooks or
    listvars, split those hooks or listvars into two, one program
    variable and one user variable.

Here I believe I understood that you considered this requirement to be
unacceptable.  Because of this, certain non-trivial parts of Custom
will have to be rewritten and even redesigned (at least in as far as
hooks and certain listvars are concerned) so that they no longer rely
on this assumption.  I believe this will be difficult enough.  I would
not try to redesign non broken parts of Custom.

Sincerely,

Luc.