From 856c2d4d2c1693e0ad9a08b325a379cd245f3676 Mon Sep 17 00:00:00 2001
From: Daniel Schierbeck <daniel.schierbeck@gmail.com>
Date: Fri, 9 Jan 2009 19:01:27 +0100
Subject: [PATCH] Add :allow_override option to Module#delegate

This enables one to override the delegation.

  class Name < Struct.new(:first, :last)
    def display_name
      "#{first} #{last}"
    end
  end

  class Person < Struct.new(:name)
    delegate :display_name, :to => :name, :allow_override => true
  end

  david = Person.new(:name => Name.new("David", "Hansson"))
  david.display_name  #=> "David Hansson"
  david.display_name = "DHH"
  david.display_name  #=> "DHH"
---
 .../active_support/core_ext/module/delegation.rb   |    9 ++++++---
 activesupport/test/core_ext/module_test.rb         |   13 +++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/activesupport/lib/active_support/core_ext/module/delegation.rb b/activesupport/lib/active_support/core_ext/module/delegation.rb
index fb4b5f0..f842824 100644
--- a/activesupport/lib/active_support/core_ext/module/delegation.rb
+++ b/activesupport/lib/active_support/core_ext/module/delegation.rb
@@ -111,10 +111,13 @@ class Module
     allow_nil = options[:allow_nil] && "#{to} && "
 
     methods.each do |method|
+      name = "#{prefix}#{method}"
+      allow_override = options[:allow_override] && "@#{method} || "
+      attr_writer name if options[:allow_override]
       module_eval(<<-EOS, "(__DELEGATION__)", 1)
-        def #{prefix}#{method}(*args, &block)                           # def customer_name(*args, &block)
-          #{allow_nil}#{to}.__send__(#{method.inspect}, *args, &block)  #   client && client.__send__(:name, *args, &block)
-        end                                                             # end
+        def #{name}(*args, &block)                                                       # def customer_name(*args, &block)
+          #{allow_override}#{allow_nil}#{to}.__send__(#{method.inspect}, *args, &block)  #   @customer_name || client && client.__send__(:name, *args, &block)
+        end                                                                              # end
       EOS
     end
   end
diff --git a/activesupport/test/core_ext/module_test.rb b/activesupport/test/core_ext/module_test.rb
index a5d9850..2894c4b 100644
--- a/activesupport/test/core_ext/module_test.rb
+++ b/activesupport/test/core_ext/module_test.rb
@@ -34,6 +34,7 @@ Someone   = Struct.new(:name, :place) do
   delegate :street, :city, :to => :place
   delegate :state, :to => :@place
   delegate :upcase, :to => "place.city"
+  delegate :display_name, :to => :name, :allow_override => true
 end
 
 Invoice   = Struct.new(:client) do
@@ -51,6 +52,10 @@ class Name
   def initialize(first, last)
     @full_name = "#{first} #{last}"
   end
+
+  def display_name
+    @full_name
+  end
 end
 
 $nowhere = <<-EOF
@@ -163,6 +168,14 @@ class ModuleTest < Test::Unit::TestCase
     assert_equal 'yz/zy', Yz::Zy.as_load_path
     assert_equal 'yz', Yz.as_load_path
   end
+
+  def test_allow_override
+    david = Someone.new(Name.new("David", "Hansson"))
+    assert_equal "David Hansson", david.display_name
+
+    david.display_name = "DHH"
+    assert_equal "DHH", david.display_name
+  end
 end
 
 module BarMethodAliaser
-- 
1.5.6.3