Add chruby support to Ruby layer

[bjeanes]

Tested locally (I use Chruby personally). I'm not sure how chruby.el fairs in other configurations as I've not used it much before. It seems closely modelled after rbenv.el.

[alindeman]

LGTM 👍 I am currently using chruby in a private layer and it's just fine. The code is basically the same as what you have here.

[semmons99]

Any movement on getting this merged into develop @syl20bnr?

[syl20bnr]

You don't need the lambda expression here you can replace it by 'chruby-use-corresponding. The lambda expression (or a named function) is needed only when you have to pass arguments to the function to hook.

[bjeanes]

Yup I can change that, I was trying to be consistent with the rbenv expression directly above this.

[bjeanes]

@syl20bnr bump for the questions above so I can fix this up and have it be merged.

[nixmaniack]

@bjeanes Take a look at documentation of use-package to understand more about :init and :config. syl20bnr already explained in brief actually, since :defer is t the package won't be loaded until ruby mode is invoked. :config is called after package is loaded. So you need to bind the hooks in :init so when you open ruby file for the first time, hooks will cause the package to autoload automagically.

One more thing to improve would be to only install/load the package when the binary is found on the system. Something like following should help in use-package
:if (executable-find "chruby")

[bjeanes]

@nixmaniack I have read those docs. My still-unanswered question is that rbenv directly above is structured exactly like my addition. What makes chruby different here, especially since the chruby script is a minimal fork of the rbenv one.

One more thing to improve would be to only install/load the package when the binary is found on the system. Something like following should help in use-package: :if (executable-find "chruby")

That does sound good. But, likewise, this is not being done in the case of the other ruby managers. Why not consistency first?

[nixmaniack]

@bjeanes That as well needs to be fixed then. I'm not sure why it may have skipped from the review but one reason I see is that the use-package v2.0 has some major changes with respect :init and :config and it may have made much sense at that time but it breaks with current version. So any new code will be reviewed from that point of view. Hope I make sense. 😄

Right now we're aiming for correctness rather than consistency but yes we should definitely fix the other ruby-version-managers sooner.

[bjeanes]

@nixmaniack OK fair enough. I'll try to have a look at this again in a few days

[StreakyCobra]

#4065 Is about chruby too, so if one get merged, the other should be closed.

[syl20bnr]

Thank you !
Sorry I forgot this PR.
I made some changes to it and fixed rbenv and rvm configuration accordingly, the documentation can be found here: https://github.com/syl20bnr/spacemacs/tree/develop/layers/%2Blang/ruby#ruby-version-management
Cherry-picked into develop branch, you can safely delete your branch.