Re: Emacs version compatibility

[Lars Ingebrigtsen <larsi@gnus.org>]

Michael Albinus <michael.albinus@gmx.de> writes:

> Sure. First step into this direction could be a modularization of that
> compat library into compat22.el, compat23.el, xcompat.el.

I was thinking the opposite.  :-)  All the items should check explicitly
for whatever they want to do, and not rely on Emacs versions at all.

That is, if you want to have `help-function-arglist' defined, then check
whether it's undefined, and then define it.  If you want a recursive
`delete-directories', then check the version of that function that's
installed, and if it's not satisfactory, then define a version that is.

So this would be orthogonal to the Emacs versions.  (Well, sort of.  The
function (re)definitions wouldn't necessarily work on all Emacs versions
that have ever been, so they need to check whether they can actually do
what they're trying to do.  Or give up.  Like this:

(when (and (not (fboundp 'help-function-arglist))
	   (fboundp 'function-arglist))
  (defun help-function-arglist (def &optional preserve-names)
     ))

So if you're on an Emacs that doesn't even have `function-arglist', then
you won't get this function.

-- 
(domestic pets only, the antidote for overdose, milk.)
  http://lars.ingebrigtsen.no  *  Sent from my Rome