Refactor Module.delegate

activesupport/lib/active_support/core_ext/module/delegation.rb

@@ -109,7 +109,7 @@ def delegate(*methods)
       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_]/
+    if options[:prefix] == true && to.to_s =~ /^[^a-z_]/
       raise ArgumentError, "Can only automatically set the delegation prefix when delegating to a method."
     end
 
@@ -119,24 +119,27 @@ def delegate(*methods)
     line = line.to_i
 
     methods.each do |method|
-      on_nil =
-        if options[:allow_nil]
-          'return'
-        else
-          %(raise "#{self}##{prefix}#{method} delegated to #{to}.#{method}, but #{to} is nil: \#{self.inspect}")
+      method_name = prefix + method.to_s
+      module_eval(<<-EOS, file, line - 1)
+        def #{method_name}(*args, &block)
+          ActiveSupport::Delegation.perform(self, #{to}, #{method.inspect}, #{method_name.inspect}, #{options[:allow_nil].inspect}, #{options[:to].inspect}, args, block)
         end
-
-      module_eval(<<-EOS, file, line - 5)
-        def #{prefix}#{method}(*args, &block)               # def customer_name(*args, &block)
-          #{to}.__send__(#{method.inspect}, *args, &block)  #   client.__send__(:name, *args, &block)
-        rescue NoMethodError                                # rescue NoMethodError
-          if #{to}.nil?                                     #   if client.nil?
-            #{on_nil}                                       #     return # depends on :allow_nil
-          else                                              #   else
-            raise                                           #     raise
-          end                                               #   end
-        end                                                 # end
       EOS
     end
   end
 end
+
+module ActiveSupport
+  module Delegation #:nodoc:
+    def self.perform(object, target, method, method_name, allow_nil, to, args, block)
+      target.__send__(method, *args, &block)
+    rescue NoMethodError
+      if target.nil?
+        return nil if allow_nil
+        raise "#{object.class}##{method_name} delegated to #{to}.#{method}, but #{to} is nil: #{object.inspect}"
+      else
+        raise
+      end
+    end
+  end
+end