Simple CLI arguments parser

parsecli.py

'''Simple CLI arguments parser

Requires the `--key=value` format. Defaults to True if value is omitted.

(C) 2018 Adam C. Abernathy, [email protected]
'''
import sys


def coerce_value(value=None):
    '''Attempts to coerce a value into either float, bool or string'''
    if not isinstance(value, str):
        return value

    try:
        return float(value)
    except:
        # Assume NaN, so test for boolean
        if value.upper() in ('TRUE', 'FALSE'):
            return True if value.upper() == 'TRUE' else False
        else:
            return value


def parse_cli(accepted_args={}, parse_all=False):
    '''Parse CLI arguments'''
    parse_all = True if parse_all or len(accepted_args.keys()) == 0 else False


    for item in sys.argv:
        try:
            key = (item.split('--')[1]).split('=')[0]

            _value = (item.split('--')[1]).split('=')
            value = _value[1] if len(_value) > 1 else True

            if parse_all:
                accepted_args[key] = coerce_value(value)
            elif key in accepted_args:
                    accepted_args[key] = coerce_value(value)
            else:
                pass

        except IndexError:
            pass
        except ValueError:
            pass
        except:
            print 'Error parsing CLI arguments!'
            return None

    return accepted_args


if __name__ == "__main__":

    accepted_args = {
        'file': None,
        'verbose': None,
    }

    print parse_cli(accepted_args)
    print parse_cli(accepted_args, True)
    print parse_cli()