Create command line interface from function definition

climatik.py

"""
climatik v0.0.1

Create command line interface from function definition
"""

import inspect
import argparse

def command(fnc, *args, **kwargs):
    """Build command line from function
    
    @command
    def mycommand(positional, optional="default", switch:bool, switchoff=True):
      ...
    """

    parser = argparse.ArgumentParser(description=fnc.__doc__)

    sig = inspect.signature(fnc)
    for k in sig.parameters:
        param = sig.parameters[k]
        name = param.name
        arg = {}

        # let's use annotation type for argument type
        if not param.annotation is param.empty:
            arg['type'] = param.annotation

        # if param has default value, argument is optional
        if not param.default is param.empty:
            name = "--"+name
            arg['default'] = param.default
            arg['type'] = type(param.default)

        # if argument type is bool, the argument become a switch
        if 'type' in arg and arg['type'] is bool:
            if not name.startswith('--'):
                name = "--"+name
            if not 'default' in arg:
                arg['action']="store_true"
            else:
                arg['action']="store_" + str(not arg['default']).lower()
                del arg['default']
            del arg['type']

        # "arg_name" to "arg-name"
        name = name.replace("_", "-")
        parser.add_argument(name, **arg)

    def _main():
        nsargs = parser.parse_args()
        args = vars(nsargs)
        kwargs = { k.replace("-","_"): args[k] for k in args }
        return fnc(**kwargs)

    fnc.main = _main
    return fnc


if __name__=="__main__":

    @command
    def mytest(name, is_pal:bool, greeting="Hi"):
        """Greet the user"""
        theend = "!" if is_pal else ""
        print("{} {}{}".format(greeting, name, theend))

    mytest.main()

$ python3 climatik.py --help
usage: climatik.py [-h] [--is-pal] [--greeting GREETING] name

Greet the user

positional arguments:
  name

optional arguments:
  -h, --help           show this help message and exit
  --is-pal
  --greeting GREETING