From 7ba538580c692b63e65c45b3cc973c02e5635897 Mon Sep 17 00:00:00 2001
From: Michael Parrish <mtparrish@gmail.com>
Date: Tue, 1 Mar 2011 13:17:19 -0600
Subject: [PATCH] Updating attr_accessor_with_default to work as expected with collections. [#6496 state:resolved]

---
 .../core_ext/module/attr_accessor_with_default.rb  |   26 ++++++++++++++++----
 .../module/attr_accessor_with_default_test.rb      |   12 +++++++++
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/activesupport/lib/active_support/core_ext/module/attr_accessor_with_default.rb b/activesupport/lib/active_support/core_ext/module/attr_accessor_with_default.rb
index e3259a0..23efb95 100644
--- a/activesupport/lib/active_support/core_ext/module/attr_accessor_with_default.rb
+++ b/activesupport/lib/active_support/core_ext/module/attr_accessor_with_default.rb
@@ -19,12 +19,28 @@ class Module
   #   attr_accessor_with_default(:element_name) { name.underscore }
   #
   def attr_accessor_with_default(sym, default = Proc.new)
-    define_method(sym, block_given? ? default : Proc.new { default })
     module_eval(<<-EVAL, __FILE__, __LINE__ + 1)
-      def #{sym}=(value)                          # def age=(value)
-        class << self; attr_accessor :#{sym} end  #   class << self; attr_accessor :age end
-        @#{sym} = value                           #   @age = value
-      end                                         # end
+      class << self; attr_reader :#{sym} end
+      
+      def #{sym}=(value)
+        class << self; attr_accessor :#{sym} end
+        @#{sym} = value
+      end
     EVAL
+
+    if block_given?
+      define_method(sym, default)
+    else
+      module_eval(<<-EVAL, __FILE__, __LINE__ + 1)
+        def #{sym}
+          class << self; attr_accessor :#{sym} end
+          @#{sym} = self.class.#{ sym }.duplicable? ? self.class.#{ sym }.dup : self.class.#{ sym }
+        end
+      EVAL
+    end
+
+    module_eval do
+      instance_variable_set "@#{ sym }", default
+    end
   end
 end
diff --git a/activesupport/test/core_ext/module/attr_accessor_with_default_test.rb b/activesupport/test/core_ext/module/attr_accessor_with_default_test.rb
index b9b60c4..9953f36 100644
--- a/activesupport/test/core_ext/module/attr_accessor_with_default_test.rb
+++ b/activesupport/test/core_ext/module/attr_accessor_with_default_test.rb
@@ -25,6 +25,18 @@ class AttrAccessorWithDefaultTest < Test::Unit::TestCase
     assert_nil(@instance.foo)
   end
 
+  def test_default_with_collection
+    @target.attr_accessor_with_default :foo, [0, 0]
+    assert_equal([0, 0], @instance.foo)
+    @instance.foo[0] = :bar
+    assert_equal([:bar, 0], @instance.foo)
+
+    new_instance = @target.new
+    assert_equal([0, 0], new_instance.foo)
+    new_instance.foo = [:bar, :baz]
+    assert_equal([:bar, :baz], new_instance.foo)
+  end
+
   def test_invalid_args
     assert_raise(ArgumentError) {@target.attr_accessor_with_default :foo}
   end
-- 
1.7.1.1