python,使用枚舉類，面向對象高級編程

python

#針對常量
#枚舉類型定義一個class類型，然后，每個常量都是class的一個唯一實例。

from enum import Enum

Month = Enum('Month', ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'))
#這樣我們就獲得了Month類型的枚舉類

for name, member in Month.__members__.items():
    print(name, '=>', member, ',', member.value)
#value屬性則是自動賦給成員的int常量，默認從1開始計數。

如果需要更精確地控制枚舉類型，可以從Enum派生出自定義類：

from enum import Enum, unique

@unique
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
#@unique裝飾器可以幫助我們檢查保證沒有重復值。

#訪問這些枚舉類型可以有若干種方法：

day1 = Weekday.Mon
print(day1)Weekday.Mon
print(Weekday['Tue'])   Weekday.Tue
print(Weekday.Tue.value)  2
print(Weekday(1))   Weekday.Mon
print(day1 == Weekday(1))True

for name, member in Weekday.__members__.items():
    print(name, '=>', member)
#結果
Sun => Weekday.Sun
Mon => Weekday.Mon
Tue => Weekday.Tue
Wed => Weekday.Wed
Thu => Weekday.Thu
Fri => Weekday.Fri
Sat => Weekday.Sat