Parse a working directory from the arguments with argparse, validating that the directory exists

parse_working_dir.py

import argparse
import os


def directory(raw_path):
    if not os.path.isdir(raw_path):
        raise argparse.ArgumentTypeError('"{}" is not an existing directory'.format(raw_path))
    return os.path.abspath(raw_path)


parser = argparse.ArgumentParser()
parser.add_argument('--working-dir', type=directory, default=os.path.curdir)
args = parser.parse_args()
print(args.working_dir)