Subject: RE: bug#27348: 24.5; [PATCH] let defvars benefit from defcustom keywords and persistence

From: Drew Adams <[email-masked]>
Date: Mon, 24 Jun 2019 11:04:40 -0700 (PDT)

> > The ability to type-check, provide :set and :initialize trigger
> > functions, automatically :require libraries, add links to doc, associate
> > with one or more :groups, etc. - these are useful things to be able to
> > do with at least some defvars, not just with defcustoms.  Similarly, the
> > ability to persist non-option variables in a user's custom file can be
> > useful.
> 
> I think this is an interesting idea, but perhaps a bug report isn't the
> right venue for it?  Did you take this up on emacs-devel?
> 
> (And here's my two pennies on the subject after considering it for about
> 60 seconds: I'm not sure this sort of extension of the type system is
> that useful...  If we want a more expressive type system in Emacs, this
> is the wrong place to start.)

It's an enhancement request. This is the place for that.

And yes, I brought it up on emacs-devel some time ago.
(Probably was told to file an enhancement request. ;-))

This is not an "extension of the [Lisp] type system".

It simply gives Lisp programmers the ability to use
some `defcustom' features for variables that users
do not change using Customize.

It separates such features, which are useful for
programmers, from the use of Customize.