Use locale.nl_langinfo in _strptime.py

[brettcannon]

BPO	8915
Nosy	@abalkin

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

Show more details

GitHub fields:

assignee = 'https://github.com/abalkin'
closed_at = None
created_at = <Date 2010-06-06.03:35:08.311>
labels = ['3.7', 'type-feature', 'library']
title = 'Use locale.nl_langinfo in _strptime'
updated_at = <Date 2016-09-10.18:34:48.582>
user = 'https://github.com/brettcannon'

bugs.python.org fields:

activity = <Date 2016-09-10.18:34:48.582>
actor = 'belopolsky'
assignee = 'belopolsky'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2010-06-06.03:35:08.311>
creator = 'brett.cannon'
dependencies = []
files = []
hgrepos = []
issue_num = 8915
keywords = []
message_count = 3.0
messages = ['107181', '107445', '125958']
nosy_count = 1.0
nosy_names = ['belopolsky']
pr_nums = []
priority = 'low'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue8915'
versions = ['Python 3.7']

[brettcannon]

It might perform better to use locale.nl_langinfo to get the current locale's datetime information instead of reverse-engineering from strftime (need to benchmark to see if this is true). This would need to be conditional as the datetime info might not be exposed through nl_langinfo.

[abalkin]

See also bpo-8957. If this happens, I would like to add a pure python implementation strftime. See also bpo-7989.

[abalkin]

I would also like to consider using OS strptime on platforms with a decent implementation.

[StanFromIreland]

Not fully possible, nl_langinfo doesn't support LC_TIME.

We can partially use it, ~33% faster.

def _getlang():
    lang = locale.setlocale(locale.LC_TIME, None)
    encoding = locale.nl_langinfo(locale.CODESET)

    return lang, encoding

$ python3.14 -m timeit -s "from _strptime import _getlang" "_getlang()"
1000000 loops, best of 5: 298 nsec per loop
$ ./python -m timeit -s "from _strptime import _getlang" "_getlang()"
1000000 loops, best of 5: 203 nsec per loop                    # ~33% faster

Caching the information will result in a decent performance gain.

[StanFromIreland]

I would also like to consider using OS strptime on platforms with a decent implementation.

This should be a separate issue.

[StanFromIreland]

@picnixz _strptime is currently pure python. This does not need the extension-modules label. It does however need the performance label :-)

[picnixz]

I never know which part of the date/time API is duplicated in C and which one is not so thanks.