How to use different versions of a gem at the same time

Question

Can I use two versions of a gem in one application?

I'm trying to use two Rails plugins to work together:

• Pengwynn's LinkedIn for LinkedIn API calls, has an dependency on OAuth (~> 0.3.5)
• OmniAuth for user login via multiple well-known websites, has an dependency on OAuth 0.4.0

When I try something in Rails I get this error message:

$ rails server
c:/Ruby187/lib/ruby/gems/1.8/gems/bundler-1.0.7/lib/bundler/resolver.rb:129:in `resolve': Bundler could not find compatible versions for gem "oauth": (Bundler::VersionConflict)
  In snapshot (Gemfile.lock):
    oauth (0.4.4)

  In Gemfile:
    linkedin depends on
      oauth (~> 0.3.5)

Running `bundle update` will rebuild your snapshot from scratch, using only
the gems in your Gemfile, which may resolve the conflict.

Trying bundle update freezes my terminal.

Is it possible to use both plugins at the same time?

Answer 1

Using two versions of a single gem usually means: use two versions of the same class.

It's not possible without making modifications to these gems. You may try to place created classes in some module, resolve conflicts in methods imported into other classes, and so on. In general, it is not easy task, and usually the effect is not worth it.

What you should do in such cases is to ask the gem maintainers to update the dependencies, or try to do it yourself.

Maybe you can downgrade (use older version of) one of these gems, to the version in which the dependencies were the same.