# File lib/bundler/ruby_version.rb, line 12
    def initialize(versions, patchlevel, engine, engine_version)
      # The parameters to this method must satisfy the
      # following constraints, which are verified in
      # the DSL:
      #
      # * If an engine is specified, an engine version
      #   must also be specified
      # * If an engine version is specified, an engine
      #   must also be specified
      # * If the engine is "ruby", the engine version
      #   must not be specified, or the engine version
      #   specified must match the version.

      @versions = Array(versions).map do |v|
        op, v = Gem::Requirement.parse(v)
        op == "=" ? v.to_s : "#{op} #{v}"
      end

      @gem_version        = Gem::Requirement.create(@versions.first).requirements.first.last
      @input_engine       = engine && engine.to_s
      @engine             = engine && engine.to_s || "ruby"
      @engine_versions    = (engine_version && Array(engine_version)) || @versions
      @engine_gem_version = Gem::Requirement.create(@engine_versions.first).requirements.first.last
      @patchlevel         = patchlevel
    end