[Python-bugs-list] [ python-Bugs-660098 ] New style classes and __hash__
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Mon, 30 Dec 2002 10:44:24 -0800
Bugs item #660098, was opened at 2002-12-30 13:39
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Thomas Heller (theller)
Assigned to: Guido van Rossum (gvanrossum)
Summary: New style classes and __hash__
Initial Comment:
New style classes obviously inherit a __hash__
implementation from object which returns the id. Per
default this allows using instances as dictionary keys,
but usually with the wrong behaviour, because most
often user classes are mutable, and their contained data
should be used to calculate the hash value.
IMO one possible solution would be to change
typeobject.c:object_hash() to raise TypeError, and
change all the immutable (core) Python objects to use
_Py_HashPointer in their tp_hash slot.
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>Comment By: Guido van Rossum (gvanrossum)
Date: 2002-12-30 13:44
Message:
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There seems to be code that tries to inherit tp_hash only
when tp_compare and tp_richcompare are also inherited, but
it seems to be failing.
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