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Title: argvars: error while parsing under windows
Type: behavior Stage: resolved
Components: Library (Lib) Versions: Python 3.4
Status: closed Resolution: not a bug
Dependencies: Superseder:
Assigned To: Nosy List: icegood, paul.j3, r.david.murray
Priority: normal Keywords:

Created on 2014-06-13 12:36 by icegood, last changed 2022-04-11 14:58 by admin. This issue is now closed.

Messages (3)
msg220432 - (view) Author: Serhiy Ivanov (icegood) Date: 2014-06-13 12:36
have as:
import argparse
import sys
print (sys.argv)
parser = argparse.ArgumentParser(prog='demo')
parser.add_argument('--host -h', help='host for the server of %(prog)', nargs=1, required=True, metavar='<host>')
parser.add_argument('--port -p', help='port for the server of %(prog)', nargs=1, required=True, metavar='<port>')

and run C:\Python34\python.exe -h 1.
Will obtain:

Traceback (most recent call last):
  File "", line 7, in <module>
  File "C:\Python34\lib\", line 1717, in parse_args
    args, argv = self.parse_known_args(args, namespace)
  File "C:\Python34\lib\", line 1749, in parse_known_args
    namespace, args = self._parse_known_args(args, namespace)
  File "C:\Python34\lib\", line 1955, in _parse_known_args
    start_index = consume_optional(start_index)
  File "C:\Python34\lib\", line 1895, in consume_optional
    take_action(action, args, option_string)
  File "C:\Python34\lib\", line 1823, in take_action
    action(self, namespace, argument_values, option_string)
  File "C:\Python34\lib\", line 1016, in __call__
  File "C:\Python34\lib\", line 2348, in print_help
    self._print_message(self.format_help(), file)
  File "C:\Python34\lib\", line 2332, in format_help
    return formatter.format_help()
  File "C:\Python34\lib\", line 278, in format_help
    help = self._root_section.format_help()
  File "C:\Python34\lib\", line 208, in format_help
  File "C:\Python34\lib\", line 208, in format_help
  File "C:\Python34\lib\", line 515, in _format_action
    help_text = self._expand_help(action)
  File "C:\Python34\lib\", line 602, in _expand_help
    return self._get_help_string(action) % params
ValueError: incomplete format
msg220437 - (view) Author: R. David Murray (r.david.murray) * (Python committer) Date: 2014-06-13 13:01
You are missing an 's' after the parens.  It should be: %(prog)s
msg220457 - (view) Author: paul j3 (paul.j3) * (Python triager) Date: 2014-06-13 15:45
It's essentially the same issue as

An error in the 'help' parameter is not caught until 'print_help' is called (via 'parse_args').  

A possible improvement is to test the 'help' string during 'add_argument'.  Similar testing for 'nargs' and 'metavar' has been proposed.
Date User Action Args
2022-04-11 14:58:04adminsetgithub: 65946
2014-06-13 15:45:27paul.j3setnosy: + paul.j3
messages: + msg220457
2014-06-13 13:01:45r.david.murraysetstatus: open -> closed

type: behavior

nosy: + r.david.murray
messages: + msg220437
resolution: not a bug
stage: resolved
2014-06-13 12:36:17icegoodcreate