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Merge pull request #1539 from mjhennig/with_metaclass

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Improve function with_metaclass()
This commit is contained in:
Markus Unterwaditzer 2015-07-27 19:25:27 +02:00
commit 7f38674915
1 changed files with 4 additions and 13 deletions
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17
flask/_compat.py
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@ -54,23 +54,14 @@ else:
def with_metaclass(meta, *bases): def with_metaclass(meta, *bases):
"""Create a base class with a metaclass."""
# This requires a bit of explanation: the basic idea is to make a # This requires a bit of explanation: the basic idea is to make a
# dummy metaclass for one level of class instantiation that replaces # dummy metaclass for one level of class instantiation that replaces
# itself with the actual metaclass. Because of internal type checks # itself with the actual metaclass.
# we also need to make sure that we downgrade the custom metaclass class metaclass(type):
# for one level to something closer to type (that's why __call__ and
# __init__ comes back from type etc.).
#
# This has the advantage over six.with_metaclass in that it does not
# introduce dummy classes into the final MRO.
class metaclass(meta):
__call__ = type.__call__
__init__ = type.__init__
def __new__(cls, name, this_bases, d): def __new__(cls, name, this_bases, d):
if this_bases is None:
return type.__new__(cls, name, (), d)
return meta(name, bases, d) return meta(name, bases, d)
return metaclass('temporary_class', None, {}) return type.__new__(metaclass, 'temporary_class', (), {})
# Certain versions of pypy have a bug where clearing the exception stack # Certain versions of pypy have a bug where clearing the exception stack