Glyn Millington writes:
Don't know how to do this with custom.el
There are ways to choose which custom.el gets loaded at runtime, but I
think it's a bad idea, since custom is basically opaque and
version-blind. If you must, example code that shows how to deal with
custom.el is in the sample init.el (available from the Help menu).
This might be another way ....
(if (and (featurep 'mule)
(emacs-version>= 21 5 0))
This is what I would recommend. Note that code that might be shared
with GNU Emacs can condition on (featurep 'xemacs).
Another possibility would be to use the desktop package. While the
use case hasn't been specified in detail, I suppose that there's a
good chance that the usage of different versions would be spatially
separated (ie, operating on files in different directories). If
that's the case, then you could save the desktop file into the working
directory, and start XEmacs from the same place. This isn't what
desktop is designed for, exactly, but it should work.
Also, I know that the OP is working on packages. If the issue is to
use XEmacs 21.4 to compile packages, but he would prefer to use 21.5
to edit code, then -batch -vanilla doesn't read user customizations in
any case. Thus setting XEMACS to point at xemacs-21.4 in the
Local.rules file and always using make to compile libraries would do
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