Re: JIT Emacs parallel world

["Phillip Lord" <phillip.lord@russet.org.uk>]

On Fri, October 19, 2018 11:18 am, Emanuel Berg wrote:
> I think the easiest way to get my gear from
> Emacs 24 to Emacs 27 JIT is to start over and
> bring stuff over one piece at a time, correcting each error/warning as I go
> along.
>
> So the current situation is, I have Emacs 24
> installed from the repos, I have Emacs-w3m installed from the repos, I have
> all my gear in a directory in ~/.emacs.d, which is loaded from ~/.emacs -
> all everyday stuff in other words.
>
> Emacs 27 JIT tho I got from Git and built
> manually - if that is the right word - but I didn't install it. So I have
> it in a directory all to itself.
>
> Now, in order to carry out my plan, how can
> I tell Emacs 27 JIT to look for another init
> file (NOT the one I have for Emacs 24, ~/.emacs), and use another Emacs
> directory (NOT ~/.emacs.d) ?


This is not the right way to do things. Emacs-27 is currently not released
and liable to be unstable. The jit branch is more so. Updating from an old
version (Emacs-24) to an unstable branch is not going to leave you in a
good place to debug any issues.

First, move your stuff from Emacs-24 to Emacs-26 -- either one you build
or a pre-compiled version. If want to try Emacs-27 with the JIT branch, do
so from there; there is a reasonably good change that you will have to
make no configuration changes between 26 and 27 (jit or otherwise).
Install as many packages as you can via package.el. Personally, I modify
`package-user-dir'  so that it includes the version number and
auto-install packages with use-package, but this is probably not
necessary.

Finally, I would use `git worktree` so that you can have both Emacs-27 and
Emacs-27 JIT branch compiled and ready to go. If you are going to live on
an unstable Emacs you may find yourself needing to switch periodically.