Python类方法、静态方法和实例方法的区别

#-*- encoding:utf-8 -*-

class Date(object):
    def __init__(self, year, month, day):
        self.year = year
        self.month = month
        self.day = day

    #实例方法
    def tomorrow(self):
        self.day +=1

    #静态方法（缺点：需要写入固定的类方法名Date）
    @staticmethod
    def parse_from_string(data_str):
        year, month, day = tuple(data_str.split("-"))
        return Date(int(year), int(month), int(day))

    #类方法(传入cls类本身,无需固定类方法名Date)
    @classmethod
    def parse_string(cls, data_str):
        year, month, day = tuple(data_str.split("-"))
        return cls(int(year), int(month), int(day))

    def __str__(self):
        return "{year}/{month}/{day}".format(year=self.year, month=self.month, day=self.day)

if __name__ == "__main__":
    data_str = "2018-6-29"
    #调用实例方法
    data = Date(2018,6,29)
    data.tomorrow()
    print(data)
    #调用静态方法
    print(Date.parse_from_string(data_str))
    #调用类方法
    print(Date.parse_string(data_str))