从C系语言过来用Python，好不容易适应了写代码不打花括号，突然有一天发现它居然木有枚举……于是stackoverflow了一把，发现神人的枚举（enum）实现到处都是，于是汉化总结过来。

如果是新版Python用户（Python 3.4 with ）：

from enum import EnumAnimal = Enum('Animal', 'ant bee cat dog')

 

or

class Animals(Enum):    ant = 1    bee = 2    cat = 3    dog = 4

 

旧版Python用户可以充分发挥动态语言的优越性来构造枚举，有简单的：

def enum(**enums):    return type('Enum', (), enums)Numbers = enum(ONE=1, TWO=2, THREE='three')# Numbers.ONE == 1, Numbers.TWO == 2 and Numbers.THREE == 'three'

 

有复杂的：

def enum(*sequential, **named):    enums = dict(zip(sequential, range(len(sequential))), **named)    return type('Enum', (), enums)Numbers = enum('ZERO', 'ONE', 'TWO')# Numbers.ZERO == 0 and Numbers.ONE == 1

 

有带值到名称映射的：

def enum(*sequential, **named):    enums = dict(zip(sequential, range(len(sequential))), **named)    reverse = dict((value, key) for key, value in enums.iteritems())    enums['reverse_mapping'] = reverse    return type('Enum', (), enums)# Numbers.reverse_mapping['three'] == 'THREE'

 

有用set实现的：

class Enum(set):    def __getattr__(self, name):        if name in self:            return name        raise AttributeErrorAnimals = Enum(["DOG", "CAT", "HORSE"])print Animals.DOG

 

有用range实现的：

dog, cat, rabbit = range(3)# orclass Stationary:    (Pen, Pencil, Eraser) = range(0, 3)print Stationary.Pen

 

有用tuple实现的：

class Enum(tuple): __getattr__ = tuple.indexState = Enum(['Unclaimed', 'Claimed'])print State.Claimed

 

有用namedtuple实现的：

from collections import namedtupledef enum(*keys):    return namedtuple('Enum', keys)(*keys)MyEnum = enum('FOO', 'BAR', 'BAZ')# 带字符数字映射的，像C/C++def enum(*keys):    return namedtuple('Enum', keys)(*range(len(keys)))# 带字典映射的，可以映射出各种类型，不局限于数字def enum(**kwargs):    return namedtuple('Enum', kwargs.keys())(*kwargs.values())