I submitted the patch to make the csv module use an OrderedDict in DictReader. It doesn't, AFAIR, use anything but the ordering property of ordered dict, so the reversion to a simple dict should be perfectly OK as long as no consumers have started to make use of specific OrderedDict properties.

regards
Steve Holden


On Thu, Jan 31, 2019 at 7:55 AM INADA Naoki <songofacandy@gmail.com> wrote:
Hi,

csv.DictReader uses OrderedDict by default, from Python 3.6.
But it doesn't make sense anymore, like namedtuple._asdict().
How about changing default dict type back to regular dict.

Python is widely used for handling learge data.  So I think
changing default dict type to OrderedDict was performance
and memory usage regression in 3.6.

Additionally, configparser uses OrderedDict by default from Python 3.6 too.

I am not sure about `parser['section1'] == parser['section2']` is not used yet.
But we broke it once in 3.6 by changing dict to OrderedDict.  Are there any
issue report caused by this backward incompatibility?

And I think performance and memory efficiency is not so important for
configparser, unlike csv.

I'm

* +1 about changing csv.DictReader's default dict type
* +0.5 about changing configparser's default dict type.

How do you think?

Regards,
--
INADA Naoki  <songofacandy@gmail.com>
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