Python enumeration class

This article mainly introduces the use of enumeration classes in Python, for more information, see: Python Learning Guide

When we need to define constants, one way is to use uppercase variables to define them by integers, such as the month:

=1=2=3=11=12

The advantage is simple, OK is the type is int , and still is the variable.

A better approach is to define a class type for such an enumeration type, and then each constant is a unique instance of class. Python provides the Enum ability to implement this feature:

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

This gives us the Month enumeration value of the type, which can be used directly Month.Jan to reference a constant, or to enumerate all its members:

forin Month.__members__.items():    print'=>'',', member.value)

valueproperty is automatically assigned to a member int constant, which is counted by default from the 1 start.

If you need to control the enumeration type more precisely, you can Enum derive the custom class from:

@uniqueclass Weekday(Enum):    =0    =1    =2    =3    =4    =5    =6

@uniqueAdorners can help us check that there are no duplicate values

There are several ways to access these enumeration types:

>>>Day1=Weekday.mon>>> Print(Day1) Weekday.mon>>> Print(Weekday.tue) Weekday.tue>>> Print(weekday[' Tue '].name) Tue>>> Print(Weekday.Tue.value)2>>> Print(Day1==Weekday.mon)True>>> Print(Day1==Weekday.tue)False>>> Print(Weekday (1)) Weekday.mon>>> Print(Day1==Weekday (1))True>>>Weekday (7Traceback (most recent): ...ValueError:7  is  notA valid Weekday>>>  forName, memberinchWeekday.__members__.items (): ...Print(Name,' = ', member) ... Sun=Weekday.sunmon=Weekday.montue=Weekday.tuewed=Weekday.wedthu=Weekday.thufri=Weekday.frisat=Weekday.sat

Python enumeration class