Description

e-kwsm

opened on May 22, 2024

Issue body actions

Feature or enhancement

Proposal:

At the moment, argparse.BooleanOptionalAction gives e.g. --foo vs --no-foo, whose prefix is hardcoded:

cpython/Lib/argparse.py

Line 848 in cd516cd

option_string = '--no-' + option_string[2:]

cpython/Lib/argparse.py

Line 863 in cd516cd

setattr(namespace, self.dest, not option_string.startswith('--no-'))

It would be beneficial if we can change the prefixes of the binary options: e.g. --enable- vs --disable- like autoconf.

usage: [-h] [--enable-foo | --disable-foo]

options:
  -h, --help            show this help message and exit
  --enable-foo, --disable-foo
                        helpstring for foo

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Activity

1. e-kwsm

   added

   type-featureA feature request or enhancementA feature request or enhancement

   on May 22, 2024
2. aisk

   added

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   on May 22, 2024
3. serhiy-storchaka

   added this to Argparse issueson May 22, 2024
4. serhiy-storchaka

   moved this to Features in Argparse issueson Oct 11, 2024
5. serhiy-storchaka

   self-assigned this

   on Oct 23, 2024
6. serhiy-storchaka commented on Oct 26, 2024

   

   serhiy-storchaka

   on Oct 26, 2024

   Member

   More actions

   This looks like reasonable request. But what API do you want?

   1. Two new parameters for positive and negative suffixes.

      parser.add_argument('--enable-foo', action=BooleanOptionalAction, true_prefix='--enable-', false_prefix='--disable-')

   2. Single parameter that takes a pair of suffixes.

      parser.add_argument('--enable-foo', action=BooleanOptionalAction, prefixes=('--enable-', '--disable-'))

   3. Simply a parameter for negative option strings.

      parser.add_argument('--enable-foo', action=BooleanOptionalAction, negative_option_strings=['--disable-foo'])
7. mpkocher commented on Jun 29, 2025

   

   mpkocher

   on Jun 29, 2025

   Contributor

   More actions

   In general, there's a lot going on in function signature to .add_argument already, I'm not sure that adding more keyword args is really going to help here.

   Also, note that the currently hardcoded values have a fundamental issue with custom prefix_chars to ArgumentParser.

    p = ArgumentParser(prefix_chars='++')
    p.add_argument("++alpha", action=BooleanOptionalAction, help="Enable Alpha mode")

   Perhaps, just documenting a recipe for this use case is reasonable.

   def _add_bool_optional_group(p: ArgumentParser, dest: str, /, *, enable: str, disable: str, required:bool=True) -> ArgumentParser:
       g = p.add_mutually_exclusive_group(required=required)
       g.add_argument(enable, action='store_true', help=f"Enable {dest}", dest=dest, default=None)
       g.add_argument(disable, action='store_false', help=f"Disable {dest} ", dest=dest, default=None)
       return p
   
   
   def to_parser() -> ArgumentParser:
       p = ArgumentParser(description="Example Tool", prog="example.py")
       return _add_bool_optional_group(p, "alpha_mode", enable="--alpha", disable="--disable-alpha", required=False)

Issue actions