Author ncoghlan
Recipients Arfrever, alex, barry, docs@python, eric.snow, ethan.furman, mark.dickinson, mjacob, ncoghlan, python-dev, serhiy.storchaka, vstinner
Date 2015-02-28.12:00:50
SpamBayes Score -1.0
Marked as misclassified Yes
Message-id <1425124851.13.0.0055077947299.issue17576@psf.upfronthosting.co.za>
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OK, something appears to have gotten confused along the way here. Barry's original problem report was that operator.index() was returning a different answer than operator.__index__() for int subclasses. Absolutely nothing to do with the int builtin at all. While the fact int() *may* return int subclasses isn't especially good, it's also a longstanding behaviour.

The problem Barry reports, where a subclassing based proxy type isn't reverting to a normal integer when accessed via operator.index() despite defining __index__() to do exactly that should be possible to fix just by applying the stricter check specifically in PyNumber_Index.

Expanding the scope to cover __int__() and __trunc__() as well would be much, much hairier, as those are much older interfaces, and used in a wider variety of situations. We specifically invented __index__() to stay away from that mess while making it possible to explicitly indicate that a type supports a lossless conversion to int rather than a potentially lossy one.
History
Date User Action Args
2015-02-28 12:00:51ncoghlansetrecipients: + ncoghlan, barry, mark.dickinson, vstinner, Arfrever, alex, docs@python, ethan.furman, python-dev, eric.snow, serhiy.storchaka, mjacob
2015-02-28 12:00:51ncoghlansetmessageid: <1425124851.13.0.0055077947299.issue17576@psf.upfronthosting.co.za>
2015-02-28 12:00:51ncoghlanlinkissue17576 messages
2015-02-28 12:00:50ncoghlancreate