模拟Enum

enum.py

class Animal:
    DOG = 1
    CAT = 2
    assert DOG == 1
    assert CAT == 2

class Enum(set):
    def __getattr__(self, name):
        if name in self:
            return name
        raise AttributeError

class Enum(tuple): __getattr__ = tuple.index

from collections import namedtuple
def enum(*keys):
    return namedtuple('Enum', keys)(*keys)

# With sequential number values
def enum(*keys):
    return namedtuple('Enum', keys)(*range(len(keys)))

# From a dict / keyword args
def enum(**kwargs):
    return namedtuple('Enum', kwargs.keys())(*kwargs.values())

def enum(**enums):
    '''simple constant "enums"'''
    return type('Enum', (object,), enums)

from recordtype import recordtype
def enum(*keys):
    return recordtype('Enum', keys)(*keys)

if __name__ == '__main__':

	animals = Enum(["DOG", "CAT", "HORSE"])
	print animals.DOG

	print Animal.DOG

	MyEnum = enum('FOO', 'BAR', 'BAZ')
	print MyEnum.FOO