Ethan Furman added the comment:
Benjamin Peterson added the comment:
>
> I consider this to be a feature. Properties can raise AttributeError to defer
> to
> __getattr__.
Micah Friesen added the comment:
>
>I submit that this is not a feature - I can't imagine a real-world scenario
>[...]
No need to imagine. The new Enum class uses this ability to support having
both protected properties on enum members and enum members of the same name:
--> from enum import Enum
--> class Field(Enum):
--> name = 1
... age = 2
... location = 3
...
--> Field.name
<Field.name: 1>
--> Field.name.name
'name'
Enum's custom __getattr__ is located in the metaclass, however, not in the
class. For future reference, here is a short test script and it's output in
3.4.0a2+:
=====================================================================================
class WithOut:
@property
def huh(self):
return self.not_here
class With:
@property
def huh(self):
return self.not_here
def __getattr__(self, name):
print('looking up %s' % name)
raise AttributeError('%s not in class %s' % (name, type(self)))
try:
WithOut().huh
except AttributeError as exc:
print(exc)
print()
try:
With().huh
except AttributeError as exc:
print(exc)
print()
import enum # broken value property tries to access self.not_here
class TestEnum(enum.Enum):
one = 1
print(TestEnum.one.value)
=====================================================================================
'WithOut' object has no attribute 'not_here'
looking up not_here
looking up huh
huh not in class <class '__main__.With'>
meta getattr with __new_member__
meta getattr with __new_member__
meta getattr with one
'TestEnum' object has no attribute 'not_here'
=====================================================================================
----------
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue1615>
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