Re: Experimental features

[Stefan Monnier]

> I don't mind adding some new features to minor releases.

I know, but I think for example that the vc-bzr.el and vc-hg.el (and
potentially others, I hope we'll get vc-darcs.el soon) are somewhat
dangerous to add to Emacs-22.[23...] unless we disable them by default:
they're not 100% modular since they normally get involved every time we open
a file (in 99% of the cases they'll just bail saying that they're not
interested in this file, but still).

So just like we have obsolete features, we could have experimental features,
which are completely deactivated by default but can easily be activated by
the user.  This might allow us to safely include a few more new features in
minor releases.

> We've already added some for Emacs 22.2.  They should be totally modular,
> though, so that we know they are safe.

I'll send a patch soon, to give a more concrete idea of my I'm thinking of.
Basically, I currently picture it as adding something like a function
(activate-experimental-feature <feature>).  And this
`activate-experimental-feature' would simply check for a function
`activate-experimental-feature-<feature>' and call it if it exists (and
otherwise do nothing).  Additionally, we would add a file-local variable
"experimental-feature" to Elisp files which would cause `autoload.el' to
wrap all the autoloads of this file into a function called
`activate-experimental-feature-<feature>'.


        Stefan