descrintro: error describing __new__ behavior

[ggenellina]

BPO	1686597
Nosy	@birkenfeld

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/birkenfeld'
closed_at = <Date 2007-08-24.06:19:26.922>
created_at = <Date 2007-03-23.09:47:15.000>
labels = ['docs']
title = 'descrintro: error describing __new__ behavior'
updated_at = <Date 2007-08-24.06:19:26.891>
user = 'https://bugs.python.org/ggenellina'

bugs.python.org fields:

activity = <Date 2007-08-24.06:19:26.891>
actor = 'georg.brandl'
assignee = 'georg.brandl'
closed = True
closed_date = <Date 2007-08-24.06:19:26.922>
closer = 'georg.brandl'
components = ['Documentation']
creation = <Date 2007-03-23.09:47:15.000>
creator = 'ggenellina'
dependencies = []
files = []
hgrepos = []
issue_num = 1686597
keywords = []
message_count = 5.0
messages = ['31634', '31635', '31636', '31637', '55244']
nosy_count = 3.0
nosy_names = ['georg.brandl', 'ggenellina', 'bethard']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue1686597'
versions = []

[ggenellina]

descrintro (http://www.python.org/download/releases/2.2.3/descrintro/#__new__) linked from http://www.python.org/doc/newstyle/ still says:

"__new__ must return an object. [...] If you return an object of a different class, its __init__ method will be called."

But since Revision 26220 - Modified Sat Apr 6 01:05:01 2002 UTC (4 years, 11 months ago) by gvanrossum:

"Changed new-style class instantiation so that when C's __new__ method returns something that's not a C instance, its __init__ is not called. [SF bug bpo-537450]"

That is, exactly the opposite as said on descrintro. The documentation for __new__ in the Reference manual, section 3.4.1, is correct and says: "If __new__() does not return an instance of cls, then the new instance's __init__() method will not be invoked."

Note that the modified behavior was already present on version 2.2.3 (and later) so updating the document currently at /download/releases/2.2.3/ would be fine.

[bethard]

Note that this is correct in the documentation: http://docs.python.org/ref/customization.html

[ggenellina]

Yes, but descrintro is the very first reference under http://www.python.org/doc/newstyle/ "and should be your starting point." (citing that page)

Surely there are other documents a bit outdated, but being descrintro in such a prominent place, should have a correct content.

[bethard]

Sorry, I wasn't suggesting that it shouldn't be corrected. Only that there's already text available to correct it in the Reference.

[birkenfeld]

Fixed in pydotorg rev. 10972.