delegate (Module)

    # File lib/active_support/core_ext/module/delegation.rb, line 99
      def delegate(*methods)
        options = methods.pop
        unless options.is_a?(Hash) && to = options[:to]
          raise ArgumentError, "Delegation needs a target. Supply an options hash with a :to key as the last argument (e.g. delegate :hello, :to => :greeter)."
        end

        if options[:prefix] == true && options[:to].to_s =~ /^[^a-z_]/
          raise ArgumentError, "Can only automatically set the delegation prefix when delegating to a method."
        end

        prefix = options[:prefix] && "#{options[:prefix] == true ? to : options[:prefix]}_"

        file, line = caller.first.split(':', 2)
        line = line.to_i

        methods.each do |method|
          on_nil =
            if options[:allow_nil]
              'return'
            else
              %(raise "#{prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}")
            end

          module_eval("def \#{prefix}\#{method}(*args, &block)               # def customer_name(*args, &block)\n\#{to}.__send__(\#{method.inspect}, *args, &block)  #   client.__send__(:name, *args, &block)\nrescue NoMethodError                                # rescue NoMethodError\nif \#{to}.nil?                                     #   if client.nil?\n\#{on_nil}\nelse                                              #   else\nraise                                           #     raise\nend                                               #   end\nend                                                 # end\n", file, line)
        end
      end