Allow unprefixed version numbers in .ruby-version

[konklone]

It seems only helpful to allow someone to specify 2.1.0 instead of ruby-2.1.0.

rbenv appears to feel strongly about the bare 2.1.0 convention, and are currently issuing warnings when ruby-2.1.0 is used. They've said they'll drop these warnings if chruby and rvm will accept a 2.1.0 convention and assume a ruby- prefix.

This seems all to the good to me - reduces confusion and enhances consistency.

[postmodern]

chruby merely passes the contents of .ruby-version to the chruby function. chruby simply uses fuzzy matching, so the following version strings all work: ruby, 1.9, ruby-1.9, ruby-1.9.3-p484.

chruby and ruby-install both encourages the use of the ruby- prefix, so that chruby 2.1.0 does not accidentally select rubinius-2.1.0 instead of ruby-2.1.0.

[konklone]

How about having 2.1.0 default to ruby-2.1.0 in case of a tie (if multiple are installed)?

[postmodern]

@konklone we could possibly do that, however chruby's selection algorithm is predictable and simple. Simply iterate the $RUBIES array, check for an exact match or a sub-string match, and use the last match.

[konklone]

Hmm - perhaps the easiest way to do it is to tweak the ordering of $RUBIES such that ruby- prefixed Rubies always end up as the last option. I suspect it would naturally already for the popular options I can think of, but it seems like you'd want a higher guarantee than that.

[postmodern]

@konklone users can append arbitrary paths to $RUBIES or override it entirely. This would require sorting $RUBIES each time it is iterated; in such a way that avoids implicit keyword splitting. I posted the question on twitter, so hopefully some actual users will post feedback.

[aprescott]

If #217 were implemented and RUBIES contained globs, ruby-* could be at the end, which would duplicate the directory entries but would effectively allow ruby-* to take precedence by being at the end.

[aprescott]

For example:

$ tree
.
├── a
├── b
├── foo-a
├── foo-b
├── foo-x
├── foo-y
├── x
└── y

$ echo {*,foo-*}
a b foo-a foo-b foo-x foo-y x y foo-a foo-b foo-x foo-y

[aprescott]

@postmodern I think users who are appending paths to RUBIES should be aware that they're changing the precedence anyway, so "your RUBIES will not be sorted" would be reasonable enough, I think.

[postmodern]

@aprescott unfortunately me nor @havenwood could not find a way to specify dir globs as Strings and expand them in a for loop, but avoid implicit keyword splitting.