Re: Incorporating caching into defgroup/defcustom/defvar for Emacs 25

[Stefan Monnier <monnier@iro.umontreal.ca>]

I'd welcome such a mechanism, and clearly various packages roll their
own, so it would be great to introduce something that can be used by
those packages (e.g. desktop.el and savehist.el could make use of such
a thing, obviously).

But I don't see much benefit from trying to link it to Custom (at most,
maybe Custom could be changed to make use of it internally).
E.g. I don't see the benefit of

     :group 'sx
over
     :dir "sx"

Also, based on the desktop.el and Gnus use cases, it seems important to
be able to save a state which is not in a variable (e.g. the frame
configuration), and it's also important that those persistent vars don't
be reloaded eagerly at init time, but later on when the corresponding
package is loaded/activated.


        Stefan