Python - 静态函数(staticmethod), 类函数(classmethod), 成员函数 区别(完全解析)

Posted 2020-10-13 SpikeKing

静态函数(staticmethod), 类函数(classmethod), 成员函数的区别(完全解析)

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

定义:

静态函数(@staticmethod): 即静态方法,主要处理与这个类的逻辑关联, 如验证数据;

类函数(@classmethod):即类方法, 更关注于从类中调用方法, 而不是在实例中调用方法, 如构造重载;

成员函数: 实例的方法, 只能通过实例进行调用;

代码:

# -*- 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)

输出:

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>

具体应用:

比如日期的方法, 可以通过实例化(__init__)进行数据输出;

可以通过类方法(@classmethod)进行数据转换;

可以通过静态方法(@staticmethod)进行数据验证;

代码:

# -*- 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'))

输出:

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

参考:

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