关于python：通过继承连接类变量？

inheritancepython

Concatenate class variable through inheritance?

我试图通过继承隐式连接类变量。我能升一级但不能再升一级…这真的有可能吗？

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class Base(object):
def get_crumbs(self):
crumbs = getattr(super(self.__class__, self), 'crumbs', ())
crumbs += getattr(self, 'crumbs', ())
return crumbs

class A(Base):
crumbs = ('un chasseur', )

class B(A):
crumbs = ('sachant chasser', )

class C(B):
crumbs = ('sans son chien', 'est un bon chasseur')

>>> c = C()
>>> c.get_crumbs()
>>> <type 'tuple'>: ('sachant chasser', 'sans son chien', 'est un bon chasseur')

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您可以循环访问class.__mro__元组：

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class Base(object):
def get_crumbs(self):
crumbs = []
for cls in type(self).__mro__:
crumbs.extend(getattr(cls, 'crumbs', ()))
return tuple(crumbs)

演示：

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>>> class Base(object):
... def get_crumbs(self):
... crumbs = []
... for cls in type(self).__mro__:
... crumbs.extend(getattr(cls, 'crumbs', ()))
... return tuple(crumbs)
...
>>> class A(Base):
... crumbs = ('un chasseur',)
...
>>> class B(A):
... crumbs = ('sachant chasser',)
...
>>> class C(B):
... crumbs = ('sans son chien', 'est un bon chasseur')
...
>>> c = C()
>>> c.get_crumbs()
('sans son chien', 'est un bon chasseur', 'sachant chasser', 'un chasseur')

旁注：永远不要使用super(self.__class__, self)。如果您重写get_crumbs()方法并使用super()调用原始方法，这将导致无限递归，请参阅如何使用super()避免无限递归？。请改用super(ClassName, self)或(仅限python 3)super()。

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