Message 258276 - Python tracker

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Author	vstinner
Recipients	eric.smith, poostenr, steven.daprano, ubehera, vstinner
Date	2016-01-15.08:15:26
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1452845726.72.0.186564910152.issue26118@psf.upfronthosting.co.za>
In-reply-to

Content
I implemented overkill optimization in _PyUnicodeWriter API used by str.format() and str%args. If the result is the input, the string is not copied by value, but by reference. >>> x="hello" >>> ("%s" % x) is x True >>> ("{}".format(x)) is x True If the format string adds something before/after, the string is duplicated: >>> ("x=%s" % x) is x False >>> ("x={}".format(x)) is x False The optimization is implemented in _PyUnicodeWriter_WriteStr(): https://hg.python.org/cpython/file/32a4e7b337c9/Objects/unicodeobject.c#l13604

I implemented overkill optimization in _PyUnicodeWriter API used by str.format() and str%args. If the result is the input, the string is not copied by value, but by reference.

>>> x="hello"
>>> ("%s" % x) is x
True
>>> ("{}".format(x)) is x
True

If the format string adds something before/after, the string is duplicated:

>>> ("x=%s" % x) is x
False
>>> ("x={}".format(x)) is x
False

The optimization is implemented in _PyUnicodeWriter_WriteStr():

https://hg.python.org/cpython/file/32a4e7b337c9/Objects/unicodeobject.c#l13604

History
Date	User	Action	Args
2016-01-15 08:15:26	vstinner	set	recipients: + vstinner, eric.smith, steven.daprano, poostenr, ubehera
2016-01-15 08:15:26	vstinner	set	messageid: <1452845726.72.0.186564910152.issue26118@psf.upfronthosting.co.za>
2016-01-15 08:15:26	vstinner	link	issue26118 messages
2016-01-15 08:15:26	vstinner	create