enum

使用Enum创建枚举类

from enum import Enum, unique

Month = Enum('Month',('Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'))

#遍历枚举类
for a in Month:
    print(a.name, ' = ', a.value) # value属性是自动赋给成员的int常量，默认从1开始计数

Jan  =  1
Feb  =  2
Mar  =  3
Apr  =  4
May  =  5
Jun  =  6
Jul  =  7
Aug  =  8
Sep  =  9
Oct  =  10
Nov  =  11
Dec  =  12

day1 = Month.Jan
print(day1.name, ' = ', day1.value)
print('day1 == Month.Jan : ', day1 == Month.Jan)
print('day1 == Month.Feb : ', day1 == Month.Feb)
print('day1 in Month : ', day1 in Month)

Jan  =  1
day1 == Month.Jan :  True
day1 == Month.Feb :  False
day1 in Month :  True

通过继承Enum创建枚举类

@unique  #装饰器可以帮助我们检查是否有重复值
class Weekday(Enum):
    Sun,Mon,Tue,Wed,Thu,Fri,Sat  = 0, 1, 2, 3, 4, 5, 6 # 也可以一个地赋值

day2 = Weekday.Sun
print('day2.name = ', day2.name)
print('day2.value = ', day2.value)
print('day2 == Weekday.Sun : ', day2 == Weekday['Sun'] )  #以字典的方式访问枚举类的值
print('day2 == Weekday.Sun : ', day2 == Weekday(0) )      #用数字获取相应的枚举类的值
print('day2 == Weekday.Wed : ', day2 == Weekday.Wed)      #以 dot 号访问枚举类的值
print('day2 in Weekday :', day2 in Weekday)

day2.name =  Sun
day2.value =  0
day2 == Weekday.Sun :  True
day2 == Weekday.Sun :  True
day2 == Weekday.Wed :  False
day2 in Weekday : True

# 下面故意在枚举类中使用重复的值, 看看会报什么错误信息
try:
    @unique
    class Sex(Enum):
        Boy = 0
        Girl = 1
        Unknown = 0
except Exception as e:
    print(e)
#从报错信息中可以看到, 枚举值 Unknown 与 Boy 重复

duplicate values found in <enum 'Sex'>: Unknown -> Boy