Python - 靜態函數(staticmethod), 類函數(classmethod), 成員函數 區別(完全解析)

原文地址：http://blog.csdn.net/caroline_wendy/article/details/23383995

還有一篇：http://blog.csdn.net/carolzhang8406/article/details/6856817

靜態函數(staticmethod), 類函數(classmethod), 成員函數的區別(完全解析)

 

定義:

靜態函數(@staticmethod): 即靜態方法,主要處理與這個類的邏輯關聯, 如驗證數據;

類函數(@classmethod):即類方法, 更關注於從類中調用方法, 而不是在實例中調用方法, 如構造重載;

成員函數: 實例的方法, 只能通過實例進行調用;

代碼:

 

# -*- coding: utf-8 -*-  
  
#eclipse pydev, python 3.3  
#by C.L.Wang  
  
class A(object):  
      
    _g = 1  
      
    def foo(self,x):  
        print('executing foo(%s,%s)'%(self,x))  
 
    @classmethod  
    def class_foo(cls,x):  
        print('executing class_foo(%s,%s)'%(cls,x))  
 
    @staticmethod  
    def static_foo(x):  
        print('executing static_foo(%s)'%x)     
  
a = A()  
a.foo(1)  
a.class_foo(1)  
A.class_foo(1)  
a.static_foo(1)  
A.static_foo('hi')  
print(a.foo)  
print(a.class_foo)  
print(a.static_foo)  

 

 

輸出:

 

 

executing foo(<__main__.A object at 0x01E2E1B0>,1)  
executing class_foo(<class '__main__.A'>,1)  
executing class_foo(<class '__main__.A'>,1)  
executing static_foo(1)  
executing static_foo(hi)  
<bound method A.foo of <__main__.A object at 0x01E2E1B0>>  
<bound method type.class_foo of <class '__main__.A'>>  
<function A.static_foo at 0x01E7E618>  

 

具體應用:

 

 

比如日期的方法, 可以通過實例化(__init__)進行數據輸出;

可以通過類方法(@classmethod)進行數據轉換;

可以通過靜態方法(@staticmethod)進行數據驗證;

 

代碼:

 

# -*- coding: utf-8 -*-

#eclipse pydev, python 3.3
#by C.L.Wang

class Date(object):

    day = 0
    month = 0
    year = 0

    def __init__(self, day=0, month=0, year=0):
        self.day = day
        self.month = month
        self.year = year

    def display(self):
        return "{0}*{1}*{2}".format(self.day, self.month, self.year)

    @classmethod
    def from_string(cls, date_as_string):
        day, month, year = map(int, date_as_string.split('-'))
        date1 = cls(day, month, year)
        return date1

    @staticmethod
    def is_date_valid(date_as_string):
        day, month, year = map(int, date_as_string.split('-'))
        return day <= 31 and month <= 12 and year <= 3999

date1 = Date('12', '11', '2014')
date2 = Date.from_string('11-13-2014')
print(date1.display())
print(date2.display())
print(date2.is_date_valid('11-13-2014'))
print(Date.is_date_valid('11-13-2014'))

 

輸出:

 

 

12*11*2014  
11*13*2014  
False  
False  

 

 

參考:

 

http://stackoverflow.com/questions/12179271/python-classmethod-and-staticmethod-for-beginner

http://stackoverflow.com/questions/136097/what-is-the-difference-between-staticmethod-and-classmethod-in-python