89-OOP之类方法和静态方法

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

    @classmethod  # 类方法，不用创建实例即可调用
    def create(cls, dstr):  # cls表示类本身, class的缩写
        y, m, d = map(int, dstr.split('-'))  # map(int, ['2000', '5', '4'])
        dt = cls(y, m, d)  # 即Date(y, m, d)
        return dt

    @staticmethod  # 静态方法，写在类的外面，可以独立成为一个函数，“愣”把它放到类中了
    def is_date_valid(dstr):
        y, m, d = map(int, dstr.split('-'))
        return 1 <= d <= 31 and 1 <= m <=12 and y < 4000

if __name__ == '__main__':
    bith_date = Date(1995, 12, 3)
    print(Date.is_date_valid('2000-5-4'))
    day = Date.create('2000-5-4')
    print(day)