Re: 28.0.50; Proposal: slightly more efficient package-quickstart.el

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

>>> Not so much, but it is not so much about noticable difference, more
>>> about not performing unnecessary computation.
> I agree that simplicity and code clarity is important, on many
> levels. But maybe we can have the cake and it it too, as you said 
> for wdired?

In the case of wdired there was a concrete gain.
Here it's only hypothetical, so the positive motivation is quite different.
Also `package-quickstart` is fairly tricky to troubleshoot (beyond removing
or refreshing the file).  To the end user it's largely a magical button,
so it's really important to make it work reliably.

IOW the incentives are strongly opposed to your proposition.

> Last weekend I tested actually myself to restructure how my packages are
> loaded. I noticed that init time increased after I added ~100 packages,
> just for test, and I didn't required anything of that into Emacs. So I
> tested the idea to put all .elc file into a single place and skipp in
> entirety this monstrosity of load-path that results after 200 packages
> are loaded. I got it to work to a degree, it least I got running Emacs,
> native compiler not complaining and most packages loaded, but I also got
> some cyclic dependency, notably for dired and semantic of all things,
> that actually rendered entire session unusable for the most part. I'll
> leave that for another day when I have some more time.

Moving the .elc files to a separate (short) list of directories indeed
one way we could address the situation where there are too many entries
on `load-path`.

Another way would be to scan `load-path` "once" and populate
a hash-table from that, after which (load "foo" ...) could be sped up by
looking up "foo" in the hash-table.

Still, that presumes that finding a file is the main issue, but I don't
know if that would indeed be true.

> (when (re-search-forward rx-path-beg nil t)
>             (goto-char (line-beginning-position))
>             (setq temp-point (point))
>             (forward-sexp)
>             (when (search-backward file nil t 1)
>               (goto-char temp-point)
>               (kill-sexp)))

I'd do something like

    (while (re-search-forward "^(add-to-list" nil t)
      (goto-char (match-beginning 0))
        (let ((start (point))
              (x (read (current-buffer))))
          ...)))


-- Stefan