__qualname__ in python 3.3
__peter__ at web.de
Sat Sep 6 20:11:01 CEST 2014
ISE Development wrote:
> Peter Otten wrote:
>> ISE Development wrote:
>>> When a class is defined within a function, the class generation
>>> function's '__qualname__' attrbute is not qualified a name.
>>> For instance:
>>> def test():
>>> class T:
>>> def method(self):
>>> t = T()
>>> When tracing a call to 'test()' using 'sys.settrace()', extracting the
>>> 'code' object from the frames of 'call' events and matching it to a
>>> 'function' object (using 'gc.get_referrers()') results in the following:
>>> 'code' object 'function' object
>>> ---------------- ------------------------------------
>>> co_name: test __qualname__: test
>>> co_name: T __qualname__: T
>>> co_name: method __qualname__: test.<locals>.T.method
>>> The second call corresponds to the class definition and not the call to
>>> the constructor (which is in fact a call to 'object.__init__', a C
>>> function hence not traced as a 'call' event - I checked this by
>>> disassembling the code object).
>>> I would expect the second call's '__qualname__' to be 'test.<locals>.T'.
>>> Can this be considered a bug? If so, I'll open one.
>> I don't understand what you are doing, so I tried to reproduce the
>> unqualified class name in 3.4 with the simpler approach of returning T:
>> Python 3.4.0 (default, Apr 11 2014, 13:05:11)
>> [GCC 4.8.2] on linux
>> Type "help", "copyright", "credits" or "license" for more information.
>>>>> def test():
>> ... class T:
>> ... def method(self): pass
>> ... return T
>>>>> T = test()
>> If you do it that way with 3.3 (I don't have it handy) do you still see
>> T instead of test.<locals>.T?
> Python 3.3 behaves in the same way in that case.
> This following shows the behaviour I am referring to:
> import gc
> import sys
> import inspect
> def global_trace(frame,event,arg):
> if event == 'call':
> code = frame.f_code
> funcs = [obj for obj in gc.get_referrers(code)
> if inspect.isfunction(obj)]
> if len(funcs) == 1:
> f = funcs
> def test():
> class C:
> def method(self):
> c = C()
> which produces:
OK, I get the same output in Python 3.4. That C seems to be an internal
function that helps build the class test.<locals>.C, and I have no
expectations as to its name. If anything I'd use something completely
different, _init_namespace_C, say.
I'm sorry I am not familiar enough with Python's internals to answer your
question -- but if in doubt, file a report.
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