Support (or not) for Emacs 21, and XEmacs

[Carsten Dominik <carsten.dominik@gmail.com>]

Hi everyone,

I am, once again, reconsidering support for Emacs 21 and XEmacs
in Org-mode.

Supporting older versions of Emacsen does make the code in
Org-mode more complex, needs time to rewrite or copy features
that do exist in newer versions of Emacs.  Also, it slows down
the process of updating the version of Org-mode distributed
with Emacs, because the compatibility code makes it often hard to
comply with Emacs rules and practices.

What I would like to do is the following.

We are now working toward release 7.0 of Org-mode, which will
hopefully see full integration of org-babel.  I am considering
to make Org-mode version 6.35 the last version of Org-mode
supporting XEmacs and Emacs 21.  That would mean that I would
still fix critical bugs in 6.35 and keep that package on the
website indefinitely.  So people stuck with Emacs 21 and XEmacs do
have an excellent version of Org-mode available.  Git users will
be able indefinitely to select this version of Org-mode to support
and Emacs 21 or XEmacs installation.

For version 7.0 I would then not only stop actively supporting
these older Emacsen, but I would actually remove some of the
twisted code that has accumulated over the years in order to
support older versions.  Important examples are all the
stuff in org-compat, but also key bindings and other stuff.  There
are about 100 cases of (featurep 'xemacs) in the sources, and many
other places where I have to check for the availablility of a
specific feature or function.

If you object to such a development, please step into this
discussion.

- Carsten