From bb0a4daddc23a7eb351fe2a6a8242d48cc21ddda Mon Sep 17 00:00:00 2001
From: Diederik van der Boor <vdboor@edoburu.nl>
Date: Sun, 7 Apr 2013 22:26:31 +0200
Subject: [PATCH] Optimize transmogrify() function, assign __class__ instead.

---
 polymorphic/query.py | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/polymorphic/query.py b/polymorphic/query.py
index 164402d..9f2cb58 100644
--- a/polymorphic/query.py
+++ b/polymorphic/query.py
@@ -19,13 +19,20 @@ Polymorphic_QuerySet_objects_per_request = CHUNK_SIZE
 
 def transmogrify(cls, obj):
     """
-    Clone an object as a different class, by instantiating that class and copying the __dict__
+    Upcast a class to a different type without asking questions.
     """
-    new = cls()
-    for k,v in obj.__dict__.items():
-        new.__dict__[k] = v
+    if not '__init__' in obj.__dict__:
+        # Just assign __class__ to a different value.
+        new = obj
+        new.__class__ = cls
+    else:
+        # Run constructor, reassign values
+        new = cls()
+        for k,v in obj.__dict__.items():
+            new.__dict__[k] = v
     return new
 
+
 ###################################################################################
 ### PolymorphicQuerySet