Re: bug-reference.el: Allow custom handlers for opening URLs

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

> So you mean we need to have a `browse-url-handlers' defcustom and a
> `browse-url-handlers-default' defvar?  Maybe you are right.  On the
> other hand, we haven't something like that for similar candidates like
> `auto-mode-alist', too.  There, we use the "if you don't like it, remove
> it yourself" approach.

Good point.  In that case the solution is to forego the use of
`defcustom`.  I'm fine with that.

After all, the autoloads are supposed to run before the .emacs, so the
user can `add-to-list` just fine to override whatever was added by autoloads.

> Symbol's value as variable is void: browse-url-mailto-function
> make[2]: *** [Makefile:584: emacs.pdmp] Error 255
> make[2]: Leaving directory '/home/horn/Repos/el/emacs/src'
> make[1]: *** [Makefile:424: src] Error 2
> make[1]: Leaving directory '/home/horn/Repos/el/emacs'
> make: *** [Makefile:1119: bootstrap] Error 2
> --8<---------------cut here---------------end--------------->8---
>
> When removing the autoload cookie, it builds fine.  Why is that?
> `browse-url-mailto-function' and `browse-url-man-function' are defined
> way before `browse-url-handlers'.

But they're not autoloaded, so in the loaddefs.el file, you have
a reference to it without the preceding definition.

Maybe the better option is to define (and use) a new function
`browse-url-mailto` (or some other name) which just funcalls
`browse-url-mailto-function`.


        Stefan