用法一：classmethod 和 staticmethod 都可以不用实例化直接调用
class demo1:
@classmethod
def c_demo(cls):
return 1
@staticmethod
def s_demo():
return 2
print(demo1.c_demo()) #1
print(demo1.s_demo()) #2
用法二：在不改变已经写好的类里面的方法的情况下，对输入的数据进行处理，在外国论坛看到一个特别好的例子
# https://stackoverflow.com/questions/12179271/meaning-of-classmethod-and-staticmethod-for-beginner
# 输出年月日，正常的情况下
class demo2:
def __init__(self, year = 0, month = 0, day = 0):
self.year = year
self.month = month
self.day = day
def out_date(self):
return "year:%d, month:%d, day:%d" % (self.year, self.month, self.day)
year = 2017
month = 7
day = 1
demo2 = demo2(year, month, day)
print(demo2.out_date())
# year:2017, month:7, day:1
# 如果用户输入的是2017-5-6格式，需要在输出前处理一下，就可以使用classmethod达到想要的效果
class demo3:
def __init__(self, year = 0, month = 0, day = 0):
self.year = year
self.month = month
self.day = day
def out_date(self):
return "year:%d, month:%d, day:%d" % (self.year, self.month, self.day)
@classmethod
def pre_out(cls, date_string):
year, month, day = map(int, date_string.split("-"))
return cls(year, month, day)
date = "2017-5-6"
year = 2017
month = 7
day = 1
try:
demo3 = demo3.pre_out(date)
except:
demo3 = demo3(year, month, day)
print(demo3.out_date())
# year:2017, month:5, day:6
