Re: A faster derived-mode-p

[Dmitry Gutov]

On 14.02.2021 22:22, Lars Ingebrigtsen wrote:
> There are only 11K commands in the Emacs tree, so I don't know whether
> the current default completion predicate is going to turn out to be
> problematically slow or not.

I just evaluated

  (length (cl-delete-if-not #'commandp obarray))

in a running Emacs session with a bunch of third-party packages 
installed and loaded, and that still evaluated only to 1083.

So if derived-mode-p only needs to run 1000 times or so, perhaps it can 
still be fast enough, however inefficient it might look. I'd also 
recommend benchmarking with both implementations, if it's really too slow.

Also see the whole other implementation approach I mentioned in another 
thread.