Add extended_by, extend_with_included_modules_from and copy_instance_variables_from to Object.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3113 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/CHANGELOG

@@ -1,5 +1,10 @@
 *SVN*
 
+* Added the following methods [Marcel Molina Jr., Sam Stephenson]:
+  * Object#copy_instance_variables_from(object) to copy instance variables from one object to another 
+  * Object#extended_by to get an instance's included/extended modules
+  * Object#extend_with_included_modules_from(object) to extend an instance with the modules from another instance
+
 * Rename Version constant to VERSION. #2802 [Marcel Molina Jr.]
 
 *1.2.3* (November 7th, 2005)

activesupport/lib/active_support/core_ext/object_and_class.rb

@@ -13,7 +13,26 @@ class Object #:nodoc:
     end
     subclasses
   end
-
+  
+  def extended_by
+    ancestors = class << self; ancestors end
+    ancestors.select { |mod| mod.class == Module } - [ Object, Kernel ]
+  end
+  
+  def copy_instance_variables_from(object, exclude = [])
+    exclude += object.protected_instance_variables if
+      object.respond_to? :protected_instance_variables
+    
+    instance_variables = object.instance_variables - exclude.map { |name| name.to_s }
+    instance_variables.each do |name|
+      instance_variable_set name, object.instance_variable_get(name)
+    end
+  end
+  
+  def extend_with_included_modules_from(object)
+    object.extended_by.each { |mod| extend mod }
+  end
+  
   # "", "   ", nil, [], and {} are blank
   def blank?
     if respond_to?(:empty?) && respond_to?(:strip)

activesupport/test/core_ext/object_and_class_ext_test.rb

@@ -6,6 +6,18 @@ class ClassB < ClassA; end
 class ClassC < ClassB; end
 class ClassD < ClassA; end
 
+module Bar
+  def bar; end
+end
+
+module Baz
+  def baz; end
+end
+
+class Foo
+  include Bar
+end
+
 class ClassExtTest < Test::Unit::TestCase
   def test_methods
     assert defined?(ClassB)
@@ -30,4 +42,66 @@ class ObjectTests < Test::Unit::TestCase
     suppress(LoadError, ArgumentError) { raise LoadError }
     suppress(LoadError, ArgumentError) { raise ArgumentError }
   end
+ 
+  def test_extended_by
+    foo = Foo.new
+    assert_equal [Bar], foo.extended_by
+    foo.extend(Baz)
+    assert_equal %w(Bar Baz), foo.extended_by.map {|mod| mod.name}.sort
+  end
+  
+  def test_extend_with_included_modules_from
+    foo, object = Foo.new, Object.new
+    assert !object.respond_to?(:bar)
+    assert !object.respond_to?(:baz)
+    
+    object.extend_with_included_modules_from(foo)
+    assert object.respond_to?(:bar)
+    assert !object.respond_to?(:baz)
+    
+    foo.extend(Baz)
+    object.extend_with_included_modules_from(foo)
+    assert object.respond_to?(:bar)
+    assert object.respond_to?(:baz)
+  end
+
 end
+
+class ObjectInstanceVariableTest < Test::Unit::TestCase
+  def setup
+    @source, @dest = Object.new, Object.new
+    @source.instance_variable_set(:@bar, 'bar')
+    @source.instance_variable_set(:@baz, 'baz')
+  end
+
+  def test_copy_instance_variables_from_without_explicit_excludes
+    assert_equal [], @dest.instance_variables
+    @dest.copy_instance_variables_from(@source)
+    
+    assert_equal %w(@bar @baz), @dest.instance_variables.sort
+    %w(@bar @baz).each do |name|
+      assert_equal @source.instance_variable_get(name).object_id, 
+                   @dest.instance_variable_get(name).object_id
+    end
+  end
+  
+  def test_copy_instance_variables_from_with_explicit_excludes
+    @dest.copy_instance_variables_from(@source, ['@baz'])
+    assert_nil @dest.instance_variable_get('@baz')
+    assert_equal 'bar', @dest.instance_variable_get('@bar')
+  end
+  
+  def test_copy_instance_variables_automatically_excludes_protected_instance_variables
+    @source.instance_variable_set(:@quux, 'quux')
+    class << @source
+      def protected_instance_variables
+        ['@bar', :@quux]
+      end
+    end
+    
+    @dest.copy_instance_variables_from(@source)
+    assert_nil @dest.instance_variable_get('@bar')
+    assert_nil @dest.instance_variable_get('@quux')
+    assert_equal 'baz', @dest.instance_variable_get('@baz')
+  end
+end