funcli.py

import re
import sys
from collections import defaultdict
from pathlib import Path
import inspect

def run(f, argv = None, *, converters = None):
	"""
		Usage:
		
		```
			def main(x: int, c: Path, b: str = '', *l: int, z: int, q: int = 0, **kw: int):
				return [x, c, b, l, z, q, kw]
			if __name__ == '__main__':
				print(funcli.run(main))
		```
	"""
	if argv is None:
		argv = sys.argv
	if converters is None:
		converters = CONVERTERS
	args, kwargs = parse_argv(sys.argv)
	args, kwargs = convert_args(args, kwargs, f, converters)
	return f(*args, **kwargs)

CONVERTERS = defaultdict(lambda: str, {
	int: int,
	float: float,
	bool: lambda s: s == 'True',
	Path: Path,
})

def convert_args(args, kwargs, f, converters):
	argspec = inspect.getfullargspec(f)
	args_converted = []
	kwargs_converted = {}
	for a, sa in zip(args, argspec.args):
		converter = converters[argspec.annotations.get(sa)]
		a_converted = converter(a)
		args_converted.append(a_converted)
	if len(args) > len(argspec.args):
		converter = converters[argspec.annotations.get(argspec.varargs)]
		for i in range(len(argspec.args), len(args)):
			a = args[i]
			a_converted = converter(a)
			args_converted.append(a_converted)
	for k, a in kwargs.items():
		if k == argspec.varargs:
			raise TypeError("{}() got an unexpected keyword argument '{}'".format(f.__name__, k))
		converter = converters[argspec.annotations.get(k or argspec.varkw)]
		a_converted = converter(a)
		kwargs_converted[k] = a_converted
	return args_converted, kwargs_converted

def parse_argv(argv):
	args = []
	kwargs = {}
	for a in argv[1:]:
		m = re.match(r'--([^=])=(.*)', a)
		if m:
			kwargs[m.group(1)] = m.group(2)
		else:
			if kwargs:
				raise SyntaxError("positional argument follows keyword argument")
			args.append(a)
	return args, kwargs