英文文檔：

classmethod(function)

Return a class method for function.

A class method receives the class as implicit first argument, just like an instance method receives the instance. To declare a class method, use this idiom:

class C:@classmethoddef f(cls, arg1, arg2, ...): ...The @classmethod form is a function decorator ? see the description of function definitions in Function definitions for details.

It can be called either on the class (such as C.f()) or on an instance (such as C().f()). The instance is ignored except for its class. If a class method is called for a derived class, the derived class object is passed as the implied first argument.

Class methods are different than C++ or Java static methods. If you want those, see staticmethod() in this section.

　 標(biāo)記方法為類方法的裝飾器

說(shuō)明：

1. classmethod 是一個(gè)裝飾器函數(shù)，用來(lái)標(biāo)示一個(gè)方法為類方法

2. 類方法的第一個(gè)參數(shù)是類對(duì)象參數(shù)，在方法被調(diào)用的時(shí)候自動(dòng)將類對(duì)象傳入，參數(shù)名稱約定為cls

3. 如果一個(gè)方法被標(biāo)示為類方法，則該方法可被類對(duì)象調(diào)用(如 C.f())，也可以被類的實(shí)例對(duì)象調(diào)用(如 C().f())

>>> class C: @classmethod def f(cls,arg1): print(cls) print(arg1) >>> C.f(’類對(duì)象調(diào)用類方法’)<class ’__main__.C’>類對(duì)象調(diào)用類方法>>> c = C()>>> c.f(’類實(shí)例對(duì)象調(diào)用類方法’)<class ’__main__.C’>類實(shí)例對(duì)象調(diào)用類方法

4. 類被繼承后，子類也可以調(diào)用父類的類方法，但是第一個(gè)參數(shù)傳入的是子類的類對(duì)象

>>> class D(C): pass>>> D.f('子類的類對(duì)象調(diào)用父類的類方法')<class ’__main__.D’>子類的類對(duì)象調(diào)用父類的類方法

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