Mailman 3 [issue23495] The writer.writerows method should be documented as accepting any iterable (not only a list) - docs

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[issue23495] The writer.writerows method should be documented as accepting any iterable (not only a list)

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Steven Barker

Feb. 20, 2015

8:45 p.m.

New submission from Steven Barker: The documentation for the csv.writer.writerows method says that it expects "a list of row objects", when it really will accept any iterable that yields rows (such as a generator). While it's often nice for code to be more accepting than the documented requirements, I think the docs in this case should state that writerows() expects an iterable, rather than misinforming users that a list is required. This documentation issue was brought up in a Stack Overflow question here: http://stackoverflow.com/questions/28636848/csv-writer-writerows-takes-itera... I expect the necessary documentation patch will be pretty trivial, and if nobody else gets to it first, I will try to provide one when I have enough time to update my cpython checkout (not soon, alas). ---------- assignee: docs@python components: Documentation messages: 236328 nosy: Steven.Barker, docs@python priority: normal severity: normal status: open title: The writer.writerows method should be documented as accepting any iterable (not only a list) type: enhancement versions: Python 2.7, Python 3.2, Python 3.3, Python 3.4, Python 3.5, Python 3.6 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue23495> _______________________________________

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Steven Barker

February 2015

1:03 a.m.

Steven Barker added the comment: Another Stack Overflow user pointed out that the DictWriter's writerows implementation (in pure Python) unnecessarily converts whatever its argument is into a list in memory before passing it on to the builtin writer.writerows method which would accept any iterable type. Probably it should be changed to use map or a generator expression instead. So, perhaps this issue isn't purely documentation, but actually a small behavior enhancement as well. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue23495> _______________________________________

SilentGhost

10:44 a.m.

Changes by SilentGhost <ghost.adh@gmail.com>: ---------- nosy: +r.david.murray _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue23495> _______________________________________

R. David Murray

2:13 p.m.

R. David Murray added the comment: Seems reasonable to me. Do you want to prepare patches? The doc patch should be separate, since it applies to all active versions, but the code change to dictwriter would go only into 3.5. ---------- stage: -> needs patch versions: -Python 3.2, Python 3.3, Python 3.6 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue23495> _______________________________________

Peter Otten

March 2015

11:57 a.m.

Changes by Peter Otten <__peter__@web.de>: ---------- nosy: +peter.otten _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue23495> _______________________________________

Martijn Pieters

April 2015

7:52 p.m.

Martijn Pieters added the comment: I'd be happy to provide a patch for the DictWriter.writerows code; I was naively counting on it accepting an iterable and that it would not pull the whole sequence into memory (while feeding it gigabytes of CSV data). ---------- nosy: +mjpieters _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue23495> _______________________________________