Message 170880 - Python tracker

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In-reply-to
Author	loewis
Recipients	Arfrever, docs@python, loewis, max
Date	2012年09月21日.11:37:37
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1348227458.62.0.400186725889.issue15997@psf.upfronthosting.co.za>

Content
The main point is: it depends on the operation. NotImplemented is a way to signal that an operation is not implemented. It can be used for whatever you want to use it for. You can design to call an operation "foo", and, if NotImplemented is returned, call "bar" instead. If you want to know how a specific operation performs its fallback, you have to look in the documentation of the specific operation. As an example for a method where some other fallback is used, see http://docs.python.org/py3k/library/abc.html#abc.ABCMeta.__subclasshook__

Content

The main point is: it depends on the operation. NotImplemented is a way to signal that an operation is not implemented. It can be used for whatever you want to use it for. You can design to call an operation "foo", and, if NotImplemented is returned, call "bar" instead.
If you want to know how a specific operation performs its fallback, you have to look in the documentation of the specific operation.
As an example for a method where some other fallback is used, see
http://docs.python.org/py3k/library/abc.html#abc.ABCMeta.__subclasshook__

History
Date	User	Action	Args
2012年09月21日 11:37:38	loewis	set	recipients: + loewis, Arfrever, docs@python, max
2012年09月21日 11:37:38	loewis	set	messageid: <1348227458.62.0.400186725889.issue15997@psf.upfronthosting.co.za>
2012年09月21日 11:37:38	loewis	link	issue15997 messages
2012年09月21日 11:37:37	loewis	create

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