Regexp based validation for argparse arguments

main.py

import argparse
import re


class Validator(object):

    def __init__(self, pattern):
        self._pattern = re.compile(pattern)

    def __call__(self, value):
        if not self._pattern.match(value):
            raise argparse.ArgumentTypeError(
                "Argument has to match '{}'".format(self._pattern.pattern))
        return value
        

class Main(object):

    email = Validator(r"^[^@]+@[^@]+\.[^@]+$")
    
    def __init__(self, handler):
        self._handler = handler
        
    def __call__(self):
        parser = argparse.ArgumentParser(description="FILL ME")
        parser.add_argument("email", type=self.email)
        args = parser.parse_args()
        
        self._handler(args.email)
        
        
def do_something(email):
    print email
    

if __name__ == '__main__':
    main = Main(do_something)
    main()