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

Question

比方說，我有一個類

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 

現在我已經延長上述各類別有具體的每一個：

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 

現在讓我們假設我打電話

SpaceShuttleGenerator.get_description() 

問題是在AdvancedGenerator我想調用SimpleGenerator中的方法傳遞類的一個實例，具體爲SpaceShuttleGenerator。這可以做到嗎？

注意：該示例已被簡化，因爲我的具體示例涉及更多。假設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()之間的區別是什麼cls將被設置爲。當直接呼叫該類時，cls設置爲SimpleGenerator，使用super()，cls將指代AdvancedGenerator。

比較你的代碼（調整使用__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)'