func2cli is a wrapper around the standard Python argparse library that intelligently passes arguments from the command line to one or more Python functions. func2cli reads the type hints and docstrings of those functions and extracts relevant information that is then passed to calls of the add_argument method of argparse parsers.

func2cli can be installed with

pip install func2cli

The example script below uses func2cli to pass command line arguments to one of two simple functions.

# script.pyfromfunc2cliimportFunctionParserdefadd_three(a: float, b: float, c: float=7) ->float:
""" Add three numbers together. Parameters ---------- a : The first number to add. b : The second number to add. c : The third number to add. Returns ------- d : The sum of a, b, and c. """returna+b+cdefmodify_string(s: str, reverse: bool=False) ->str:
""" Make a string upper case, and maybe reverse it. Parameters ---------- s : The original string. reverse : Whether to reverse the string. Returns ------- output : The modified string. """output=s.upper()
ifreverse:
output=output[::-1]
returnoutputif__name__=='__main__':
parser=FunctionParser([add_three, modify_string])
output=parser.run()
print(output)

Usage information is automatically available at the command line.

$ python script.py -husage: script.py [-h] {add-three,modify-string} ...positional arguments: {add-three,modify-string} add-three Add three numbers together. modify-string Make a string upper case, and maybe reverse it.options: -h, --help show this help message and exit

script.py has two allowed positional arguments, one for each of the functions passed to the FunctionParser. Moreover, usage information for individual positional arguments can also be displayed.

$ python script.py add-three -husage: script.py add-three [-h] [--c c] a bAdd three numbers together.positional arguments: a The first number to add. b The second number to add.options: -h, --help show this help message and exit --c c The third number to add. (default: 7)

func2cli automatically treats parameters with default values as optional command line arguments.

$ python script.py add-three 2 413.0
$ python script.py add-three 2 4 --c -8-2.0

The FunctionParser knows what types are permissible for each argument. For example, the arguments to add-three should all be floats, and so an invalid argument passed at the command line raises an error.

$ python script.py add-three 1 foousage: script.py add-three [-h] [--c c] a bscript.py add-three: error: argument b: invalid float value: 'foo'

Boolean arguments should be passed as the strings True and False. This convention breaks with traditional argparse idioms, but makes the resulting command line statements more similar to their corresponding Python function calls.

$ python script.py modify-string -husage: script.py modify-string [-h] [--reverse reverse] sMake a string upper case, and maybe reverse it.positional arguments: s The original string.options: -h, --help show this help message and exit --reverse reverse Whether to reverse the string. (default: False)
$ python script.py modify-string hello --reverse TrueOLLEH

By default, func2cli assumes that functions have type hints and docstrings that look like the ones in script.py above. However, func2cli supports arbitrary docstring conventions by allowing the user to pass a custom parse_func argument to FunctionParser.