Question about __getattribute__/__getattr__

Mark McEahern marklists at
Mon Sep 30 11:52:08 EDT 2002

>         if cached_value == None:

This is an aside, but comparison to None should be via identity rather than
equality; e.g.,

  if x is None:


  if x is not None:

Why?  Because you may be comparing an object that barfs when compared to
None via its own __eq__ method.  It's a subtle point and I don't think I'm
explaining it very well.  Suffice it to say, if you really are comparing to
None, use is/is not.  If you want to test whether an object is/is not zero,
then use:

  if x:


  if not x:

// m

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