Optionally support auto-switching

[postmodern]

Many users have requested the ability to automatically switch to a Ruby when entering a directory which contains a .ruby-version file. While in the directory and all sub-directories, the Ruby should remain set. Only when the user ascends the directory containing the .ruby-version file should chruby switch back to system Ruby.

This feature is optional and would be enabled by loading /usr/local/share/chruby/auto.sh.

[mpapis]

also consider using http://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/x264.html instead to avoid cd overwrite conflicts.

[postmodern]

I assume you'd do something like PROMPT_COMMAND="chruby_auto; $PROMPT_COMMAND"? Other than the fact the command runs on every new prompt (meaning chruby_auto would have to return quickly if no action is needed), are there any other drawbacks?

[mpapis]

I think yes, to speed up you can do:

export last_chruby_pwd=""
chruby_auto_prompt(){
  [[ "$last_chruby_pwd" == "$PWD" ]] || {
    chruby_auto
    last_chruby_pwd="$PWD"
  }
}

[steveklabnik]

👍

[postmodern]

Now using precmd_functions and PROMPT_COMMAND. This has the added benefit of automatically detecting new .ruby-version files after git pull or user creation.

[ku1ik]

Can't wait for it!

[postmodern]

Coming in 0.3.0. But first I need to release 0.2.5, with a brand new setup.sh and installation instructions that don't rely on @github's deprecated Downloads. Also still have to write extensive tests for auto-switching.

[mpapis]

just added rvm/rvm#1388 - works great

[wilmoore]

Just commented on one of the tests.

[postmodern]

Copy/pasting my comment so no one missing it.

To avoid ascending each directory in search of a .ruby-version (I assume this would degrade performance) after every command, I decided to require the user cd into the project root.

Thoughts?

[mpapis]

descending directories should not have any impact on performance, unix/linux does cache filesystem calls, so first call to a new directory might be slightly slower (like double disk seek time) but otherwise it's fast - tested it with RVM - you do not see the difference

[postmodern]

Alright, I will add an ascending search for .ruby-version, if RUBY_VERSIONED_DIR isn't already set.

[postmodern]

OK, I think I covered all the edge-cases. Please review.

[postmodern]

Hmm, @github didn't auto-link to commit bf69302. Link to source and tests.

[wilmoore]

"${dir%/*}" 👍

That said; I couldn't figure out how this protects from infinitely looping once / is reached.

[mpapis]

assertNull in shell ;)

[postmodern]

Realized that the current implementation will not allow overriding the .ruby-version with an explicit call to chruby. Is this acceptable behaviour?

[mpapis]

I do not thinks so, it's quite important to allow switching to something else, especially to try other rubies with your project

[postmodern]

Next question, if a user explicitly selects a Ruby, should entering a project with a .ruby-version file override the already selected Ruby. Trying to avoid a chicken & egg problem between chruby and chruby_auto.

[steveklabnik]

I would want entering the directory to set it to the version in .ruby-version regardless of what I've previously chosen.

[postmodern]

Ah, my mistake. Due to the if [[ "$version_file" == "$RUBY_VERSION_FILE" ]]; then return check, we allow the user to override .ruby-version while within the project. I will sleep on this and then merge into the 0.3.0 branch, if there's no other comments.

[pushcx]

I think .ruby-version is not the best name for this. It's a file specific only to chruby, and the contents are its name for your ruby (rather than some version specification that gets mapped to your ruby). In the future, it might have more info and thus be even less human-readable and generic.

I'd like to suggest .chruby or .chruby-version, similar to .rvm and .rbenv. I can put together a pull request if folks think this is a good idea and prefer one.

(And since this is the first time I've popped up on the project; thanks for making chruby, I switched a few days ago and have been really enjoying it.)

[steveklabnik]

Isn't .ruby-version supported by both rvm and rbenv?

[mpapis]

.ruby-version is supported by rvm and rbfu, there is a ticket for rbenv rbenv/rbenv#199 / rbenv/rbenv#201

[postmodern]

I do agree that the name .ruby-version implies a specific version (which is tedious) compared to fuzzy matching against a canonical Ruby name (name-version). Adding a chruby specific dot-file would increase dot-file proliferation and promote factionalism amongst Rubyists; adding tool specific dot-files to repos is the developer equivalent of flying your colors.

[pushcx]

I was totally unaware that was a shared standard, that's wonderful. I retract my suggestion. :)

[ku1ik]

I'm with @mpapis on ability to override version specified in .ruby-version with call to chruby. That's not uncommon use-case.

[wilmoore]

What should ruby -v be after the following scenario?

• cd into a directory with a .ruby-version file, thus $(ruby -v) -eq "rubinius-2.0.0-rc1".
• direct call chruby ruby-1.9.3 w/ fuzzy match; $(ruby -v) -eq "ruby-1.9.3-p327"
• cd tests -- what should ruby -v be now?

[mpapis]

@wilmoore I think it should be still what user picked in second step ruby-1.9.3-p327 - it should be reset only when user leaves context of current project / .ruby-version

[wilmoore]

it should be reset only when user leaves context of current project / .ruby-version

In the above scenario, when the user did cd tests, she moved from the root of the project to a descendant directory (still part of the project). That being the case, what takes precedent.

[postmodern]

Here's an example of the current behaviour:

[hal@tank ronin]$ pwd
/vault/1/code/ronin
[hal@tank ronin]$ cat ronin/.ruby-version 
1.9
[hal@tank ronin]$ cd ronin
[hal@tank ronin]$ chruby
   jruby-1.7.0
   rubinius-2.0.0-rc1
 * ruby-1.9.3-p327
[hal@tank ronin]$ cd lib
[hal@tank lib]$ chruby
   jruby-1.7.0
   rubinius-2.0.0-rc1
 * ruby-1.9.3-p327
[hal@tank lib]$ chruby rubinius
[hal@tank lib]$ chruby
   jruby-1.7.0
 * rubinius-2.0.0-rc1
   ruby-1.9.3-p327
[hal@tank lib]$ cd ronin/ui/cli/
[hal@tank cli]$ chruby
   jruby-1.7.0
 * rubinius-2.0.0-rc1
   ruby-1.9.3-p327
[hal@tank cli]$ cd ../../../../
[hal@tank ronin]$ pwd
/vault/1/code/ronin/ronin
[hal@tank ronin]$ chruby
   jruby-1.7.0
 * rubinius-2.0.0-rc1
   ruby-1.9.3-p327
[hal@tank ronin]$ cd ..
[hal@tank ronin]$ chruby
   jruby-1.7.0
   rubinius-2.0.0-rc1
   ruby-1.9.3-p327

[wilmoore]

Appears to work as requested.

[postmodern]

Without further ado, merging this into 0.3.0 branch.

[postmodern]

Merged. Any pre-release comments/commits should be directed towards the 0.3.0 branch.

[postmodern]

This has been released in 0.3.0.