New submission from Raymond Hettinger <[email protected]>:
Currently, Namespace() objects sort the attributes in the __repr__. This is
annoying because argument order matters and because everywhere else in the
module we preserve order (i.e. users see help in the order that arguments are
added).
Note, the docs do not promise that Namespace is displayed with a sort. This is
likely just an artifact of older dictionaries having arbitrary or randomised
ordering.
>>> from argparse import ArgumentParser
>>> parser = ArgumentParser()
>>> _ = parser.add_argument('source')
>>> _ = parser.add_argument('destination')
# Order matters to the user inputing the arguments
# (source must go first and destination must go last
>>> args = parser.parse_args(['input.txt', 'output.txt'])
# Order is preserved internally
>>> vars(args)
{'source': 'input.txt', 'destination': 'output.txt'}
# Despite this, the Namespace() repr alphabetizes the output
>>> args
Namespace(destination='output.txt', source='input.txt')
# Order is preserved in help()
>>> parser.parse_args(['-h'])
usage: [-h] source destination
positional arguments:
source
destination
optional arguments:
-h, --help show this help message and exit
----------
components: Library (Lib)
messages: 358455
nosy: rhettinger
priority: normal
severity: normal
status: open
title: argparse should preserve argument ordering in Namespace
type: enhancement
versions: Python 3.9
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Python tracker <[email protected]>
<https://bugs.python.org/issue39058>
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