Message 77657 - Python tracker

➜

This issue tracker has been migrated to GitHub, and is currently read-only.
For more information, see the GitHub FAQs in the Python's Developer Guide.

Author	tim.peters
Recipients	gregory.p.smith, nassrat, tim.peters
Date	2008-12-12.01:54:56
SpamBayes Score	5.4387878e-05
Marked as misclassified	No
Message-id	<1229046897.45.0.28118543302.issue4638@psf.upfronthosting.co.za>
In-reply-to

Content
"is" is for testing object identity, not numeric equality. That "1 is 1" is always true is simply an implementation detail common to all recent versions of CPython, due to CPython caching "very small" integer objects. The language definition neither requires nor forbids this, so any program relying on it is in error. Likewise any program relying on "1.0 is 1.0" being false is also in error.

"is" is for testing object identity, not numeric equality.  That "1 is
1" is always true is simply an implementation detail common to all
recent versions of CPython, due to CPython caching "very small" integer
objects.  The language definition neither requires nor forbids this, so
any program relying on it is in error.  Likewise any program relying on
"1.0 is 1.0" being false is also in error.

History
Date	User	Action	Args
2008-12-12 01:54:57	tim.peters	set	recipients: + tim.peters, gregory.p.smith, nassrat
2008-12-12 01:54:57	tim.peters	set	messageid: <1229046897.45.0.28118543302.issue4638@psf.upfronthosting.co.za>
2008-12-12 01:54:56	tim.peters	link	issue4638 messages
2008-12-12 01:54:56	tim.peters	create