Re: Deprecating 'lexical-binding: nil'

[Stefan Kangas <stefan@marxist.se>]

Richard Stallman <rms@gnu.org> writes:

> I support making lexical binding the default, eventually, but instead
> of proposing to make nonlexical binding mode obsolete (which implies
> removing it), let's stop with deprecating it.

That is fine by me, thank you.

Note that I was a bit careless in my choice of words here: the subject
said "deprecated" but the actual text said "obsolete".  I think
"deprecated" better communicates the intention here.

> To delete a mode of usage that was formerly the default would make it
> almost unfrasible to run old Lisp programs in newer Emacs versions.
>
> The changes required to make those old programs function with lexical
> binding are not simple or eash to write.  You can't find them by
> searching for certain names, as you could for many other incompatible
> changes.  In some cases, they require studying the code carefully.
>
> To avoid that, let's keep the nonlexical mode working.

I agree.  For the record, it was never my intention to suggest that we
should rush to delete 'lexical-binding:nil'.  My expectation is that it
will be phased out at some point in the future when it is no longer
really relevant.

Or maybe the future maintainers of Emacs will decide that it makes sense
to keep it around as a novelty.  You know, much like how most Unix-like
operating systems still come with vi.  ;-)

> I have no opinion about whether to take the first step in Emacs 28 or
> in Emacs 29.

Both our maintainers have said that they don't want this in Emacs 28,
and I can understand their reasoning.

We can revisit this after 28.1 has been released, and some time have
passed.  My hope is that we will be able to finally declare it
deprecated in Emacs 29.