use toml as config format.

toml-config-arg.py

import toml
from argparse import ArgumentParser
from os import path

import collections

# python 3.8+ compatibility
try:
    collectionsAbc = collections.abc
except:
    collectionsAbc = collections

def update(d, u):
    for k, v in u.items():
        dv = d.get(k, {})
        if not isinstance(dv, collectionsAbc.Mapping):
            d[k] = v
        elif isinstance(v, collectionsAbc.Mapping):
            d[k] = update(dv, v)
        else:
            d[k] = v
    return d

def load_config(config_path):
    print("reading config from <{}>\n".format(path.abspath(config_path)))
    try:
        with open(config_path, "r") as f:
            config = toml.load(f)
            return config
    except FileNotFoundError as e:
        print("can not find config file")
        raise e


def parse_argument():
    parser = ArgumentParser("Train")
    parser.add_argument("-c", "--config", type=str, help="config file path", required=True)
    parser.add_argument("-t", "--toml", type=str, action="append")
    options = parser.parse_args()
    return options

def main():
    options = parse_argument()
    config = load_config(options.config)
    print(config)
    
    if options.toml is not None:
    	tomls = "\n".join(options.toml)
    	new_config = toml.loads(tomls)
    	print(new_config)
    	print(update(config, new_config))

if __name__ == "__main__":
    main()

example usage:

python3 toml-arg.py -c stage1.toml -t "loss.mask_l1.weight=100" -t "log.verify.freq=10" -t "ti=[1, 2]"