classmethod must have a reference to a class object as the first parameter, whereas staticmethod can have no parameters at all.
class Date(object):
def __init__(self, day=0, month=0, year=0):
self.day = day
self.month = month
self.year = 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
date2 = Date.from_string('11-09-2012')
classmethod的第一个参数就是类本身,
cls is an object that holds class itself, not an instance of the class.
不管这个方式是从实例调用还是从类调用，它都用第一个参数把类传递过来.
staticmethod可以没有任何参数
@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
# usage:
is_date = Date.is_date_valid('11-09-2012')
就像调用一个普通函数一样,只不过这个函数在Date类里.
上面两个例子都没有创建实例就使用类里面的方法,这应该就是使用这两个装饰器的优势吧.
参考: stackoverflow
