[ python-Bugs-1263635 ] type() and isinstance() do not call __getattribute__
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Fri Aug 26 10:48:44 CEST 2005
Bugs item #1263635, was opened at 2005-08-18 21:07
Message generated for change (Comment added) made by rhettinger
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Category: Python Interpreter Core
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Submitted By: Per Vognsen (pervognsen)
Assigned to: Nobody/Anonymous (nobody)
Summary: type() and isinstance() do not call __getattribute__
Initial Comment:
The built-in functions type() and isinstance() do not call
__getattribute__ for instances of user-defined classes.
Thus, for instance,
x.__class__ == sometype
and
type(x) == sometype
can give inconsistent results.
I ran into this problem in writing a transparent
persistence system, where instances of proxy classes
are used as stand-ins for unloaded objects and the
proxy does just-in-time loading by overloading
__getattribute__ and __setattr__ (which changes
__class__).
(This applies to 2.4.1.)
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>Comment By: Raymond Hettinger (rhettinger)
Date: 2005-08-26 03:48
Message:
Logged In: YES
user_id=80475
I don't think this is going to change. A number of builtins
directly access an object's structure and do not respect
overrides via __getattribute__. This is somewhat intrinsic
the Python's current design.
----------------------------------------------------------------------
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