version action - short option customization `-v`

[WojciechMigda]

Currently, when plac.call is passed version argument, then plac adds argument for version reporting which uses -v short option.
However, it is not uncommon for CLI design to have -V being used as short option for version display, and -v for output verbosity. wget and curl have CLIs like this.

I would welcome a change which introduces customized short option for version display. -v could remain a default choice if the user does not wish to override it.

[ialbert]

I would work around these situations by defining the parameters explicitly.

In addition, if you want to protect a particular name because it also appears in the scope, you can use the underscore trick, where parameter names defined with trailing underscores will register without the underscore; here is an example:

import plac

# we need to protect this name in parameters
version = "1.0.0"

# Note the underscore in the definition and declaration below, 
@plac.flg('version_', help="print version", abbrev='V')
@plac.flg('verbose', help="print verbose", abbrev='v')
def main(version_=False, verbose=False):
    print ("version: ", version)
    print ("verbose: ", verbose)

if __name__ == '__main__':
    # Execute function via plac.call().
    plac.call(main)

then python demo.py -h will print:

usage: demo.py [-h] [-V] [-v]

options:
  -h, --help     show this help message and exit
  -V, --version  print version
  -v, --verbose  print verbose

[WojciechMigda]

I've been using a workaround like this (though using the 'type hint' approach instead of decorators), but the downside is that when I have mandatory arguments in my interface then I can't query version info without providing also those mandatory arguments.

[ialbert]

I can't fully assess the impact of adding -V to backward compatibility, which is of utmost importance for a command-line parsing library.

I will say though, that for your use case replacing -v with -V requires only changing this line:

https://github.com/ialbert/plac/blob/master/plac_core.py#L435

If this use case is important, you could add plac_core.py to your codebase and modify that line.

[WojciechMigda]

I can't fully assess the impact of adding -V to backward compatibility, which is of utmost importance for a command-line parsing library.

Maybe I was misunderstood. I am not proposing changing -v to -V, but to have a possibility to override -v as a default setting.