PeterHarding at 04:32, 21 September 2011

2011-09-21T04:32:47Z

← Older revision		Revision as of 15:32, 21 September 2011
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			=Examples=

			See - http://stackoverflow.com/questions/36932/whats-the-best-way-to-implement-an-enum-in-python

			Here are a few of these...


			==One==

			<pre>
			class Animal:
			DOG=1
			CAT=2

			x = Animal.DOG
			</pre>

			==Two==

			<pre>
			def enum(**enums):
			return type('Enum', (), enums)
			</pre>
			Used like so:

			<pre>
			>>> Numbers = enum(ONE=1, TWO=2, THREE='three')
			>>> Numbers.ONE
			1
			>>> Numbers.TWO
			2
			>>> Numbers.THREE
			'three'
			</pre>

			=Three=

			Provide automatic enumeration with something like this:

			<pre>
			def enum(sequential, *named):
			enums = dict(zip(sequential, range(len(sequential))), **named)
			return type('Enum', (), enums)
			</pre>

			Used like so:

			<pre>
			>>> Numbers = enum('ZERO', 'ONE', 'TWO')
			>>> Numbers.ZERO
			0
			>>> Numbers.ONE
			1
			</pre>

			=Four=

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

			...

			Animals = Enum(["DOG", "CAT", "Horse"])

			print Animals.DOG
			</pre>

			This can be further improved by overriding __setattr__(self, name, value) and maybe __delattr__(self, name) so that if you accidentally write Animals.DOG = CAT, it won't silently succeed.


			=Five=

			<pre>
			dog, cat, rabbit = range(3)
			</pre>

			=Five=

			<pre>
			class Animal:
			def __init__(self, name):
			self.name = name

			def __str__(self):
			return self.name

			def __repr__(self):
			return "<Animal: %s>" % self

			Animal.DOG = Animal("dog")
			Animal.CAT = Animal("cat")

			>>> x = Animal.DOG
			>>> x
			<Animal: dog>
			>>> x == 1
			False
			</pre>

			<pre>
			</pre>

			<pre>
			</pre>

	[[Category:Python]]		[[Category:Python]]

PeterHarding: Created page with ' Category:Python'

2011-09-21T04:22:45Z

Created page with ' Category:Python'

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