Performance: faster Object.subclasses_of

2 files changed, 10 insertions, 9 deletions

diff --git a/activesupport/lib/active_support/core_ext/object/extending.rb b/activesupport/lib/active_support/core_ext/object/extending.rb
index 43a2be916e..082e98a297 100644
--- a/activesupport/lib/active_support/core_ext/object/extending.rb
+++ b/activesupport/lib/active_support/core_ext/object/extending.rb
@@ -3,17 +3,18 @@ class Object
     Class.remove_class(*subclasses_of(*superclasses))
   end
 
+  # Exclude this class unless it's a subclass of our supers and is defined.
+  # We check defined? in case we find a removed class that has yet to be
+  # garbage collected. This also fails for anonymous classes -- please
+  # submit a patch if you have a workaround.
   def subclasses_of(*superclasses) #:nodoc:
     subclasses = []
 
-    # Exclude this class unless it's a subclass of our supers and is defined.
-    # We check defined? in case we find a removed class that has yet to be
-    # garbage collected. This also fails for anonymous classes -- please
-    # submit a patch if you have a workaround.
-    ObjectSpace.each_object(Class) do |k|
-      if superclasses.any? { |superclass| k < superclass } &&
-        (k.name.blank? || eval("defined?(::#{k}) && ::#{k}.object_id == k.object_id"))
-        subclasses << k
+    superclasses.each do |sup|
+      ObjectSpace.each_object(class << sup; self; end) do |k|
+        if k != sup && (k.name.blank? || eval("defined?(::#{k}) && ::#{k}.object_id == k.object_id"))
+          subclasses << k
+        end
       end
     end
 
diff --git a/activesupport/test/core_ext/class_test.rb b/activesupport/test/core_ext/class_test.rb
index 0346fad190..9c6071d478 100644
--- a/activesupport/test/core_ext/class_test.rb
+++ b/activesupport/test/core_ext/class_test.rb
@@ -38,9 +38,9 @@ class ClassTest < Test::Unit::TestCase
     @parent   = eval("class D; end; D")
     @sub      = eval("class E < D; end; E")
     @subofsub = eval("class F < E; end; F")
-    assert @parent.subclasses.all? { |i| [@sub.to_s, @subofsub.to_s].include?(i) }
     assert_equal 2, @parent.subclasses.size
     assert_equal [@subofsub.to_s], @sub.subclasses
     assert_equal [], @subofsub.subclasses
+    assert_equal [@sub.to_s, @subofsub.to_s].sort, @parent.subclasses.sort
   end
 end