New submission from tkhyn <[email protected]>:
The following script, run with python 3.6.5, highlights an issue with the
class' __name__ attribute being set incorrectly just because of a loop in the
metaclass' __new__ method:
class MC(type):
def __new__(mcs, name, bases, attrs):
for name, attr in attrs.items():
pass
return super(MC, mcs).__new__(mcs, name, bases, attrs)
class C(metaclass=MC):
a = None
print(C.__name__)
Expected output: "C"
Actual output: "a"
Comment the for loop and you get the expected output!
On Python 2.7.13, the amended code exposes the same bug:
class MC(type):
def __new__(mcs, name, bases, attrs):
for name, attr in attrs.items():
pass
return super(MC, mcs).__new__(mcs, name, bases, attrs)
class C(object):
__metaclass__ = MC
a = None
print C.__name__
output is "__metaclass__" and should be "C"
----------
components: Interpreter Core
messages: 315218
nosy: tkhyn
priority: normal
severity: normal
status: open
title: iteration over attrs in metaclass' __new__ affects class' __name__
versions: Python 2.7, Python 3.6
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Python tracker <[email protected]>
<https://bugs.python.org/issue33268>
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