Message 218582 - Python tracker

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In-reply-to
Author	vstinner
Recipients	lebedov, rhettinger, vstinner
Date	2014年05月14日.22:18:49
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1400105930.13.0.182632478399.issue21507@psf.upfronthosting.co.za>

Content
frozenset constructor has different implementations depending on the input type: set (or frozenset), dict or iterator. The constructor preallocates the frozenset for set and dict, but not for generic iterator and so the set may have a suboptimal size. Attached patch set_length_hint.patch optimizes also the 3rd case using operator.length_hint (PyObject_LengthHint in C). Since it is an optimization, I prefer to only apply it to Python 3.5 to limit the risk of regression.

Content

frozenset constructor has different implementations depending on the input type: set (or frozenset), dict or iterator. The constructor preallocates the frozenset for set and dict, but not for generic iterator and so the set may have a suboptimal size.
Attached patch set_length_hint.patch optimizes also the 3rd case using operator.length_hint (PyObject_LengthHint in C).
Since it is an optimization, I prefer to only apply it to Python 3.5 to limit the risk of regression.

History
Date	User	Action	Args
2014年05月14日 22:18:50	vstinner	set	recipients: + vstinner, rhettinger, lebedov
2014年05月14日 22:18:50	vstinner	set	messageid: <1400105930.13.0.182632478399.issue21507@psf.upfronthosting.co.za>
2014年05月14日 22:18:50	vstinner	link	issue21507 messages
2014年05月14日 22:18:49	vstinner	create

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