如何從Python中重寫的@classmethod調用父類的@classmethod？

Question

假設我有一堂課

class SimpleGenerator(object):
    @classmethod
    def get_description(cls):
        return cls.name

class AdvancedGenerator(SimpleGenerator):
    @classmethod
    def get_description(cls):
        desc = SimpleGenerator.get_description() # this fails
        return desc + ' Advanced(tm) ' + cls.adv_feature

現在我已經擴展了上面的每個類，每個類都有一個具體的類：

class StringGenerator(SimpleGenerator)
    name = 'Generates strings'
    def do_something():
        pass

class SpaceShuttleGenerator(AdvancedGenerator)
    name = 'Generates space shuttles'
    adv_feature = ' - builds complicated components'
    def do_something():
        pass

現在讓我說我打電話

SpaceShuttleGenerator.get_description()

問題是在AdvancedGenerator我想調用SimpleGenerator的方法傳遞類的實例，特別是SpaceShuttleGenerator 。 可以這樣做嗎？

注意：示例是簡化的，因為我的具體示例涉及更多。 讓我們說我的目標不是連接字符串。

Answer 1

使用super() ：

@classmethod
def get_description(cls):
    desc = super(AdvancedGenerator, cls).get_description()
    return desc + ' Advanced(tm) ' + cls.adv_feature

使用SimpleGenerator.get_description()和super(AdvancedGenerator, cls).get_description()之間的區別是cls將被設置為。 直接調用類時， cls設置為SimpleGenerator ，使用super() ， cls將引用AdvancedGenerator 。

比較你的代碼（調整為使用__name__來說明差異）：

>>> class SimpleGenerator(object):
...     @classmethod
...     def get_description(cls):
...         return cls.__name__
... 
>>> class AdvancedGenerator(SimpleGenerator):
...     @classmethod
...     def get_description(cls):
...         desc = SimpleGenerator.get_description() 
...         return desc + ' Advanced(tm)'
... 
>>> AdvancedGenerator.get_description()
'SimpleGenerator Advanced(tm)'

並使用super() ：

>>> class AdvancedGenerator(SimpleGenerator):
...     @classmethod
...     def get_description(cls):
...         desc = super(AdvancedGenerator, cls).get_description()
...         return desc + ' Advanced(tm)'
... 
>>> AdvancedGenerator.get_description()
'AdvancedGenerator Advanced(tm)'