# File lib/bundler/ruby_version.rb, line 5
    def initialize(version, 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.

      @version        = version
      @engine         = engine || "ruby"
      # keep track of the engine specified by the user
      @input_engine   = engine
      @engine_version = engine_version || version
    end