python中静态方法和类方法的区别

1.静态方法就是一个普通的方法，与类和对象无关

2.类方法就是JAVA里面的类方法，属于类，被各个对象共享

class OptSample(object):
    count = 0

    def __init__(self,origin_data):
        self.origin_data = origin_data

    @staticmethod
    def add_number(num1,num2):
        print(num1 + num2)

    @classmethod
    def total(cls):
        print(cls.count)

sample1 = OptSample(1)
sample2 = OptSample(2)
sample1.add_number(2,3)
sample1.total()
运行结果是5和0

静态方法其实和普通方法没什么差别，它的参数列表里面不会出现cls,或者self,在一定程度上解释了为什么它是类和对象无关的

class OptSample(object):
    count = 0

    def __init__(self,origin_data):
        self.origin_data = origin_data
        self.count += origin_data

    @classmethod
    def total(cls):
        print(cls.count)

sample1 = OptSample(1)
sample1.total()

结果是0，很明显self.count += origin_data 是在操作一个对象的属性而非一个类的属性,

通常在类的方法较容易操作类属性

class OptSample(object):
    count = 0

    def __init__(self,origin_data):
        self.origin_data = origin_data

    @classmethod
    def total(cls):
        cls.count += 1
        print(cls.count)

sample1 = OptSample(1)
sample1.total()
OptSample.total()

结果是1和2，类方法通过cls来操作cls
那么就单个对象而言如何在实例方法中去修改类变量？通过self.__class__

class OptSample(object):
    count = 0

    def __init__(self,origin_data):
        self.origin_data = origin_data
        self.__class__.count += origin_data
    @classmethod
    def total(cls):
        print(cls.count)

sample1 = OptSample(122)
sample1.total()
OptSample.total()

结果是122和122