Default lexical-binding to t

Default lexical-binding to t

[Stefan Monnier]

In bug#74145 I suggest that it is time to change the default of
`lexical-binding` to t.  Clearly this is a breaking change, but only for
those files which:

- Don't have a `lexical-binding` cookie.
- Have code which happens to behave differently under the new dialect
  (such code is not rare, but a lot of code works identically in the
  two dialects).

I believe by the time Emacs-31 will be released, such files will be
uncommon, and it is easy to fix them (either by adjusting he code, or
by slapping a `lexical-binding` cookie).


        Stefan

Re: Default lexical-binding to t

[Gerd Möllmann]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> In bug#74145 I suggest that it is time to change the default of
> `lexical-binding` to t.  Clearly this is a breaking change, but only for
> those files which:
>
> - Don't have a `lexical-binding` cookie.
> - Have code which happens to behave differently under the new dialect
>   (such code is not rare, but a lot of code works identically in the
>   two dialects).
>
> I believe by the time Emacs-31 will be released, such files will be
> uncommon, and it is easy to fix them (either by adjusting he code, or
> by slapping a `lexical-binding` cookie).

+1

Re: Default lexical-binding to t

[Karl Fogel]

On 01 Nov 2024, Stefan Monnier wrote:
>In bug#74145 I suggest that it is time to change the default of
>`lexical-binding` to t.  Clearly this is a breaking change, but 
>only for
>those files which:
>
>- Don't have a `lexical-binding` cookie.
>- Have code which happens to behave differently under the new 
>dialect
>  (such code is not rare, but a lot of code works identically in 
>  the
>  two dialects).
>
>I believe by the time Emacs-31 will be released, such files will 
>be
>uncommon, and it is easy to fix them (either by adjusting he 
>code, or
>by slapping a `lexical-binding` cookie).

+1  It's time.

Anecdata, but: a lot of the random Emacs packages I encounter in 
the wild lately have `lexical-binding` cookies already (and 
usually to t anyway).  Most recently 
https://github.com/kmonad/kbd-mode/blob/master/kbd-mode.el, for 
example.  No doubt there are also many that don't, but I think 
knowledge about the new dialect is diffused widely enough now that 
when Emacs' default switches over, some user of a given package 
will quickly recognize what's going on and submit the appropriate 
change to that package; in a few cases I have done so myself.

Best regards,
-Karl