init.el: setup user-emacs-directory when load

[coldnew]

user-emacs-directory is defined by emacs when load config, in most case
it's value is ~/.emacs.d. We setup this variable in init.el to make
existing emacs user can test spacemacs by

emacs -q -l ~/spacemacs/init.el

without change their own ~/.emacs.d config.

Signed-off-by: Yen-Chin Lee coldnew.tw@gmail.com

[syl20bnr]

I cherry-picked it and played with it.
There is a major problem with this approach: all after-init-hooks will be triggered right away because the hook is run before the end of the alternate init file (source) . It leads to numerous errors, I fixed the spacemacs ones but obviously I cannot fix the errors from packages. The remaining errors don't prevent spacemacs from working but they give a very bad impression on spacemacs quality with errors logs in *Messages*.

For those reasons I revert back this change as well as the documentation I added. See commit 23c2314

[syl20bnr]

Anyway thank you for the PR !

[syl20bnr]

There is a clean way to do it mentioned in the source above but it involved playing with ~/.emacs file. Although not as intrusive as making a backup of one's current configuration, it is still intrusive, so I prefer the simplicity of only one way to install it. In the end it is just a matter of moving one directory.

[coldnew]

It's ok, I use another way to suite my need without hack the spacemacs,
the reason why I want to dynamic select is because I can't give up my emacs right now,
instead, I open both spacemacs and emacs to write my code.

My method as following repo, first I load my own init.el, then set the user-emacs-directory to spacemacs-dir.

https://github.com/coldnew/coldnew-spacemacs

[syl20bnr]

That's cool. It would be cool if emacs -q -l ~/spacemacs/init.el can work without being force to code work-arounds to support it, anyway thank you I was very glad to merge your proposal but unfortunately it did not work as expected.
Your method works because you load spacemacs init inside your init.el, it requires non trivial manipulation so it is hard to offer this mechanism to someone willing to try spacemacs. It has to be simpler than renaming two folders.

[opsahl]

A better way to run spacemacs from a separate directory is to install it in
/your/chosen/path/.emacs.d/
and then run emacs like this:
env HOME=$HOME/your/chosen/path emacs &

and then you can alias the admittably ugly way of starting it to something like spacemacs