kxroberto <kxrobe...@users.sourceforge.net> added the comment:

Well, "==" whould allow the wanted feature by exception through meta classes 
for concerned classes:

>>> class X:
...     a=1
... 
>>> Y=X
>>> class X:
...     a=1
... 
>>> Y==X
False
>>> class XCompare(type):
...     def __eq__(self, other):
...             print "tolerant class __eq__"
...             return self.__name__ == other.__name__
... 
>>> class X:
...     __metaclass__ = XCompare
...     a=1
... 
>>> Y=X
>>> class X:
...     a=1
... 
>>> Y==X
tolerant class __eq__
True
>>> 


Better than nothing. Its a improvement generally, independently.
But thinking about my acutal use cases and all: It still doesn't satisfy. I 
don't want to introduce this extra magic on all those classes just for that 
feature - because when needed, the majority of classes are concerned (see 
below). One can have only one meta class ... its too tricky and off-road to 
guess for most programmers ... 

"when in doubt, raise an error": That is IMHO too rigid here, and generally 
when a feature is then hindered too much. Aren't warnings the right tool for 
such case? If really rarely there is problem, should it surface easily already 
during dev & test time?
Compared to the everday life danger of Pythons dynamic attribute access, 
version incompatibilities, etc. its about a rather harmless issue here.

Now I'd vote for a warnings.warn upon "==" (or old "is") failing , and then an 
error only when the .__name__ is not matching too. A warning at dev & test time 
should be enough, when just "==" (or "is") fails. 


I mainly like the tolerance during development: e.g. fast reload style edit-run 
cycles (reload sometimes improved with special reload fix code), because I 
noticed that 95% of code changes/bug fixes do not require a full expensive 
app-restart. This pays off particularly with bigger GUI app development/fixing 
and similar, where lot of status is accumulated expensively during run time.
But I wished that feature already for a deployed app too.

----------

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<http://bugs.python.org/issue13479>
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