Python基于staticmethod裝飾器標(biāo)示靜態(tài)方法
英文文檔:
staticmethod(function)
Return a static method for function.
A static method does not receive an implicit first argument.
The @staticmethod 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.
標(biāo)示方法為靜態(tài)方法的裝飾器
說明:
1. 類中普通的方法,實(shí)際上既可以被類直接調(diào)用也可以被類的實(shí)例對象調(diào)用,但是被實(shí)例對象調(diào)用的時候,要求方法至少有一個參數(shù),而且調(diào)用時會將實(shí)例對象本身傳給第一個參數(shù)
>>> class Student(object): def __init__(self,name): self.name = name def sayHello(lang): print(lang) if lang == ’en’: print(’Welcome!’) else: print(’你好!’) >>> Student.sayHello<function Student.sayHello at 0x02AC7810>>>> a = Student(’Bob’)>>> a.sayHello<bound method Student.sayHello of <__main__.Student object at 0x02AD03F0>>>>> Student.sayHello(’en’) # 類調(diào)用的時候,將’en’傳給了lang參數(shù)enWelcome!>>> a.sayHello() # 類實(shí)例對象調(diào)用的時候,將對象本身自動傳給了lang參數(shù),不能再接收參數(shù)<__main__.Student object at 0x02AD03F0>你好! >>> a.sayHello(’en’) Traceback (most recent call last): File '<pyshell#7>', line 1, in <module> a.sayHello(’en’) TypeError: sayHello() takes 1 positional argument but 2 were given
2. staticmethod函數(shù)功能就是將一個方法定義成類的靜態(tài)方法,正確的方法是使用 @staticmethod裝飾器,這樣在實(shí)例對象調(diào)用的時候,不會把實(shí)例對象本身傳入靜態(tài)方法的第一個參數(shù)了。
# 使用裝飾器定義靜態(tài)方法>>> class Student(object): def __init__(self,name): self.name = name @staticmethod def sayHello(lang): print(lang) if lang == ’en’: print(’Welcome!’) else: print(’你好!’) >>> Student.sayHello(’en’) #類調(diào)用,’en’傳給了lang參數(shù)enWelcome!>>> b = Student(’Kim’) #類實(shí)例對象調(diào)用,不再將類實(shí)例對象傳入靜態(tài)方法>>> b.sayHello()Traceback (most recent call last): File '<pyshell#71>', line 1, in <module> b.sayHello()TypeError: sayHello() missing 1 required positional argument: ’lang’>>> b.sayHello(’zh’) #類實(shí)例對象調(diào)用,’zh’傳給了lang參數(shù)zh你好!
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