Re: Always-true predicate?

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Stefan Kangas <stefankangas@gmail.com>,  rpluim@gmail.com,  rms@gnu.org,
>   emacs-devel@gnu.org
> Date: Fri, 19 Feb 2021 14:40:32 +0100
> 
> I think using function values in user options is fine -- the Emacs
> developers can never get cover all behavioural permutations that people
> would like to see, so allowing them to supply their own code is helpful.

Allowing a function as _one_ of the values is okay-ish, provided that
we don't do that too willy-nilly, where atoms could do the job.  One
example of what I'd like NOT to see is using 'ignore as such a
function value -- we should use nil instead.  (And likewise for the
always-true predicate being discussed here.)

But my main gripe is about options whose values can only be functions,
and nothing else.  No one will convince me that Emacs developers
cannot come up with meaningful values that aren't functions for some
option.