In argparse subparser's option goes to parent parser

[py-user]

BPO	24477
Nosy	@py-user

^{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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assignee = None
closed_at = None
created_at = <Date 2015-06-20.00:52:42.933>
labels = ['type-bug', 'library']
title = "In argparse subparser's option goes to parent parser"
updated_at = <Date 2015-06-20.00:52:42.933>
user = 'https://github.com/py-user'

bugs.python.org fields:

activity = <Date 2015-06-20.00:52:42.933>
actor = 'py.user'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2015-06-20.00:52:42.933>
creator = 'py.user'
dependencies = []
files = []
hgrepos = []
issue_num = 24477
keywords = []
message_count = 1.0
messages = ['245536']
nosy_count = 1.0
nosy_names = ['py.user']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue24477'
versions = ['Python 3.6']

[py-user]

Some misleading behaviour found with option belonging.
It's possible to put one option twicely, so it can set different
parameters accoding to context.

A source of argt.py for test:

#!/usr/bin/env python3

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('-f', dest='tf', action='store_true')

subs = parser.add_subparsers()

sub = subs.add_parser('cmd')
sub.add_argument('-f', dest='cf', action='store_true')

parser.add_argument('arg')

args = parser.parse_args()
print(args)

Running it:

[guest@localhost debug]$ ./argt.py cmd 1
Namespace(arg='1', cf=False, tf=False)
[guest@localhost debug]$ ./argt.py cmd -f 1
Namespace(arg='1', cf=True, tf=False)
[guest@localhost debug]$ ./argt.py cmd 1 -f
Namespace(arg='1', cf=False, tf=True)
[guest@localhost debug]$

ISTM, options for the top parser should be placed between program name and subcommand name in any order, and options for the subcommand should follow subcommand in any order. The argument of top parser should be moved to the end and parsed after all options were placed correctly.

[serhiy-storchaka]

I do not see anything wrong or controversial here. argparse allows to pass options after positional arguments, and in the third example it is passed after positional argument arg that belongs to the main parser. It cannot be passed to the subparser, because the subparser already finished its work, and the main parser parsed arguments that follow the subparser.