Enum類  2018/8/12 

1.應用：
定義常量時value屬性則是自動賦給成員的int常量，預設從1開始計數

from enum import Enum

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

type(Month),type(Month.Jan)#(enum.EnumMeta, <enum 'Month'>) 

屬性：
Month.Feb.name#'Feb'
Month.Feb.value#2 
 

for name, member in Month.__members__.items():
print(name, '=>', member, ',', member.value)#輸出見備註1

for i in Month:
print(i,i.name,i.value) #輸出見備註1 

2.精確地控制列舉型別從Enum派生出自定義類：

from enum import Enum, unique

@unique #檢查保證沒有重複值
class Weekday(Enum):
Sun = 0 # Sun的value被設定為0
Mon = 1
Tue = 2
Wed = 3
Thu = 4
Fri = 5
Sat = 6 
 

屬性：
day1.name# 'Mon'
day1.value#1
day1.Sun.name# 'Sun'
day1.Sun.value#0

訪問列舉型別：
day1 = Weekday.Mon #<Weekday.Mon: 1>
print(Weekday.Tue) #Weekday.Tue
print(Weekday['Tue']) #Weekday.Tue
print(Weekday.Tue.value) #2
print(Weekday(1)) #Weekday.Mon    

備註1：

輸出：