The nearest equivalent is to place a file called '.ruby-version' in the top level directory, containing the version number of the Ruby you want to use. Version numbers come from https://github.com/rbenv/ruby-build/tree/master/share/ruby-b.... rbenv, chruby and rvm all support .ruby-version.

One difference from virtualenv is that the Ruby version managers share single installations of each version of Ruby. My understanding from occasional use of Virtualenv is that it copies the python installation into a new per-project subdirectory, which seems a bit wasteful to me.

> You can set the path config variable of Bundler to not place the project Gems in a central location which I think is cleaner and try to remember to always do now.

Yes, this is what I do. It gives me a shared 'clean' Ruby installation of the right version, plus a project-specific copy of all the gems the project depends on. To me this provides the best trade off between project isolation and not duplicating the whole world. You can set bundler up so this is done automatically by creating '~/.bundle/config' containing

    ---
    BUNDLE_PATH: "vendor/bundle"
    BUNDLE_BIN: ".bundle/bin"