[Checkins] SVN: zope.app.keyreference/trunk/src/zope/app/keyreference/persistent.py point out what the optimization really is; it's not that Python's isinstance

[Fred L. Drake, Jr.]

Log message for revision 89867:
  point out what the optimization really is; it's not that Python's isinstance
  is slow, but that object state may need to be unpickled as a side effect
  

Changed:
  U   zope.app.keyreference/trunk/src/zope/app/keyreference/persistent.py

-=-
Modified: zope.app.keyreference/trunk/src/zope/app/keyreference/persistent.py
===================================================================
--- zope.app.keyreference/trunk/src/zope/app/keyreference/persistent.py	2008-08-15 05:35:22 UTC (rev 89866)
+++ zope.app.keyreference/trunk/src/zope/app/keyreference/persistent.py	2008-08-15 06:22:48 UTC (rev 89867)
@@ -63,7 +63,9 @@
         if self.key_type_id == other.key_type_id:
             # While it makes subclassing this class inconvenient,
             # comparing the object's type is faster than doing an
-            # isinstance check.
+            # isinstance check.  The intent of using type instead
+            # of isinstance is to avoid loading state just to
+            # determine if we're in conflict resolution.
             if type(self.object) is PersistentReference:
                 # We are doing conflict resolution.
                 assert isinstance(other.object, PersistentReference), (