user_name_validator.py

class UserNameValidator(object):
    """A simple user name validator to prohibit banned words"""

    not_allowed = set(['parrot','dog','kitten','ibis',])
    substitutions = {'1':'i','0':'o','7':'t'}
    
    def is_valid(self, name):
        name = name.lower()
        #Substitute values as needed in name
        for find,replace in UserNameValidator.substitutions.items():
            name = name.replace(find, replace)
        if name in UserNameValidator.not_allowed:
            return False
        return True
        
        
if __name__=='__main__':
    validator = UserNameValidator()
    test_list = ['ibis','ib1s','1bis','1b1s','k1t7en','goodname']
    for test in test_list:
        print test, validator.is_valid(test)