Re: Lexical binding: why?

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

> I was thinking more of a bug, since fixed, in older versions of the
> lexical-binding code.  Purely hypothetically at the moment, of course.
> But this code is surely not so simple that bugs can be ruled out.

Oh, so it's a hypothetical need.

> For consistency with other features, which can all be enabled
> conditionally, surely lexical-binding should also be conditionally
> enablable in a reasonable way.

Based on the 7 years of experience since Emacs-24.1 was released,
I think YAGNI is a good reason not to bother trying to implement it.

Especially since: if the file's content really does work when
lexical-binding is nil, then a simple workaround for the lack of this
feature is to keep using lexical-binding=nil until the problematic
version(s) are not supported any more and you can set
lexical-binding=t unconditionally.

While I do hope we'll be able to drop support for lexical-binding=nil in
some distant future, "distant" is an import characterization.  I'd be
amazed if this happened before 2030.


        Stefan