RE: How to customize an option to a dynamic value (computed by lisp form)

[Drew Adams]

> I want one elisp function that, even when called non-interactively,
> respects custom-set and does type-checking.

You might want to `M-x report-emacs-bug'.  It is for enhancement
requests as well as bugs.

> > A variable value is always "static", by definition of the word
> > "value".  It's not clear (to me) just what you are looking for.
>
> I am sorry.  By "static value" I meant "literal".

What does that mean?  A variable has a single, static, literal
value at any time.  That's what a value is.  What you are looking
for is still unclear (to me).  Hopefully it is clearer to others,
and they can help more.