Python: Enum枚举的实现

如果是新版Python用户（Python 3.4 with PEP 435）：

1 2	from enum import Enum Animal = Enum('Animal', 'ant bee cat dog')

 

or

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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：

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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：

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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：

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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：

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