Le Wed, 24 Apr 2013 00:22:40 +1000,
Nick Coghlan <ncogh...@gmail.com> a écrit :
>
> Looking at the source
> (https://bazaar.launchpad.net/~barry/flufl.enum/trunk/view/head:/flufl/enum/_enum.py),
> I'm not seeing any fundamental technical issues with merging the Enum
> and EnumValue class definitions, and then using "cls" where the
> metaclass code currently uses "cls.__value_factory__" (even for the
> backwards compatible variant, the 2v3 metaclass issue isn't a problem,
> you can just define a _BaseEnum class with the right metaclass using
> the 2 & 3 compatible notation and inherit from that in a normal class
> definition)
>
> However, there's one non-technical aspect of such a merger which does
> concern me, which is the fact that you would lose the distinct
> docstrings for the class and the values:
You can work it around by making __doc__ a descriptor that behaves
differently when called on a class or an instance. There is a slight
metaclass complication because __doc__ is not writable on a class (but
I suppose enums are already using a metaclass, so it's not much of an
issue):
class docwrapper:
def __init__(self, class_doc, instance_doc_func):
self.class_doc = class_doc
self.instance_doc_func = instance_doc_func
def __get__(self, instance, owner):
if instance is None:
return self.class_doc
else:
return self.instance_doc_func(instance)
def instancedocwrapper(instance_doc_func):
class metaclass(type):
def __new__(meta, name, bases, dct):
dct['__doc__'] = docwrapper(dct['__doc__'],
instance_doc_func)
return type.__new__(meta, name, bases, dct)
return metaclass
class D(metaclass=instancedocwrapper(
lambda self: "My instance:{}".format(self.x))):
"""My beautiful, documented class."""
def __init__(self, x):
self.x = x
class E(D):
"""My magnificent subclass."""
print("class doc:", D.__doc__)
print("subclass doc:", E.__doc__)
print("instance doc:", E(5).__doc__)
Note that the builtin help() function always displays the class's
__doc__, even when called on an instance which has its own __doc__.
Regards
Antoine.
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