Re: add-variable-watcher usage in lisp/frame.el

[Robert Pluim]

Noam Postavsky <address@hidden> writes:

> On 1 June 2018 at 05:18, Robert Pluim <address@hidden> wrote:
>> lisp/frame.el has:
>>
>> (mapc (lambda (var)
>>         (add-variable-watcher var (symbol-function 'set-buffer-redisplay)))
>
>> Not using symbol-function makes this output (set-buffer-redisplay)
>> instead, which I think looks better, Iʼm wondering why symbol-function
>> was used?
>
> Passing a subr object tells the variable watcher mechanism to call the
> C function directly (without a possible GC call), which is closer to
> what happened in Emacs 25 (see diff of [1: d3faef9bae]). I don't know
> that it's really needed in this case though.

Thanks for the explanation. By all means lets avoid adding potential GC to code
thatʼs not expecting it.

Robert