From 794d93f7a5ede9801929ef2a5292a0380f0700b5 Mon Sep 17 00:00:00 2001
From: Jamis Buck <jamis@37signals.com>
Date: Wed, 26 Apr 2006 17:46:43 +0000
Subject: [PATCH] Added Module#alias_method_chain

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4276 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
---
 activesupport/CHANGELOG                          |  2 ++
 .../lib/active_support/core_ext/module.rb        |  1 +
 .../active_support/core_ext/module/aliasing.rb   | 16 ++++++++++++++++
 3 files changed, 19 insertions(+)
 create mode 100644 activesupport/lib/active_support/core_ext/module/aliasing.rb

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index e38eb9ad31..3a4b4e477f 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Added Module#alias_method_chain [Jamis Buck]
+
 * Updated to Builder 2.0 [DHH]
 
 * Add Array#split for dividing arrays into one or more subarrays by value or block. [Sam Stephenson]
diff --git a/activesupport/lib/active_support/core_ext/module.rb b/activesupport/lib/active_support/core_ext/module.rb
index e67cf940f6..45069f52af 100644
--- a/activesupport/lib/active_support/core_ext/module.rb
+++ b/activesupport/lib/active_support/core_ext/module.rb
@@ -3,3 +3,4 @@
 require File.dirname(__FILE__) + '/module/delegation'
 require File.dirname(__FILE__) + '/module/introspection'
 require File.dirname(__FILE__) + '/module/loading'
+require File.dirname(__FILE__) + '/module/aliasing'
diff --git a/activesupport/lib/active_support/core_ext/module/aliasing.rb b/activesupport/lib/active_support/core_ext/module/aliasing.rb
new file mode 100644
index 0000000000..a80ff0f26d
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/module/aliasing.rb
@@ -0,0 +1,16 @@
+class Module
+  # Encapsulates the common pattern of:
+  #
+  #   alias_method :foo_without_feature, :foo
+  #   alias_method :foo, :foo_with_feature
+  #
+  # With this, you simply do:
+  #
+  #   alias_method_chain :foo, :feature
+  #
+  # And both aliases are set up for you.
+  def alias_method_chain(target, feature)
+    alias_method "#{target}_without_#{feature}", target
+    alias_method target, "#{target}_with_#{feature}"
+  end
+end