Working with bundler and different platform gem requirements

Question

I seem to struggling with what I thought was standard functionality of bundler, according the manual The ability to specifiy that gems should be required on for certain platforms using the :platforms option or platforms block

I want to specifcy a different version of a gem dependent on the version of ruby used

source "http://rubygems.org"
gem "trollop", "~> 1.16.2"
gem "chronic", "~> 0.6.4"
gem "highline", "~> 1.6.2"
gem "colorize", "~> 0.5.8"
gem "queryparams", "~> 0.0.3"

platforms :ruby_18 do
  gem "json"
  gem "activesupport", "~>2.8.9"
end

platforms :ruby_19 do
  gem "activesupport", "~>3.1.3"
end

However this fails when running bundle install

You cannot specify the same gem twice with different version requirements.
You specified: activesupport (~> 2.8.9) and activesupport (~> 3.1.3)

Answer 1

You don't need 2 different Gemfiles in order to achieve platform-specific gem-requirements. Just check for the RUBY_VERSION and put your gems in some sort of conditional clause:

if(defined?(JRUBY_VERSION))
  gem 'warbler'
else
  case(RUBY_VERSION)
  when('1.8.7')
    gem 'ruby-debug'
  when('1.9.2')
    gem 'ruby-debug19'
  when('1.9.3')
    gem 'debugger'
  end
end

That should do the trick.

With best regards,