Add Object#instance_exec and Proc#bind

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3469 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/CHANGELOG

@@ -1,5 +1,9 @@
 *SVN*
 
+* Add Object#instance_exec, like instance_eval but passes its arguments to the block.  (Active Support will not override the Ruby 1.9 implementation of this method.) [Sam Stephenson]
+
+* Add Proc#bind(object) for changing a proc or block's self by returning a Method bound to the given object. Based on why the lucky stiff's "cloaker" method. [Sam Stephenson]
+
 * Fix merge and dup for hashes with indifferent access #3404 [kenneth.miller@bitfield.net]
 
 * Fix the requires in option_merger_test to unbreak AS tests. [Sam Stephenson]

activesupport/lib/active_support/core_ext/object_and_class.rb

@@ -65,6 +65,12 @@ def instance_values
   def to_json
     ActiveSupport::JSON.encode(self)
   end
+
+  unless defined? instance_exec # 1.9
+    def instance_exec(*arguments, &block)
+      block.bind(self)[*arguments]
+    end
+  end
 end
 
 class Class #:nodoc:

activesupport/lib/active_support/core_ext/proc.rb

@@ -0,0 +1,12 @@
+class Proc #:nodoc:
+  def bind(object)
+    block, time = self, Time.now
+    (class << object; self end).class_eval do
+      method_name = "__bind_#{time.to_i}_#{time.usec}"
+      define_method(method_name, &block)
+      method = instance_method(method_name)
+      remove_method(method_name)
+      method
+    end.bind(object)
+  end
+end

activesupport/test/core_ext/object_and_class_ext_test.rb

@@ -111,4 +111,10 @@ def test_instance_values
     object.instance_variable_set :@b, 2
     assert_equal({'a' => 1, 'b' => 2}, object.instance_values)
   end
+
+  def test_instance_exec_passes_arguments_to_block
+    block = Proc.new { |value| [self, value] }
+    assert_equal %w(hello goodbye), 'hello'.instance_exec('goodbye', &block)
+  end
+
 end

activesupport/test/core_ext/proc_test.rb

@@ -0,0 +1,12 @@
+require 'test/unit'
+require File.dirname(__FILE__) + '/../../lib/active_support/core_ext/proc'
+
+class ProcTests < Test::Unit::TestCase
+  def test_bind_returns_method_with_changed_self
+    block = Proc.new { self }
+    assert_equal self, block.call
+    bound_block = block.bind("hello")
+    assert_not_equal block, bound_block
+    assert_equal "hello", bound_block.call
+  end
+end