I decided to resume my (limited) Python skills after not coding for a long time.

Here's a very simple self-contained program to convert the characters of an email address into their HTML entities (the purpose is to make the email invisible to spamrobots).

  • Any comment for improvement? (e.g. args parsing, code style, etc.)

  • Apart from the -h option in argparse, what is the standard way to add some documentation for it, such as a manpage or some embedded help?


# mung - Convert a string into its HTML entities

import argparse

parser = argparse.ArgumentParser(description = 'Convert a string into its HTML entities.')
parser.add_argument('string_to_mung', help = 'String to convert')
parser.add_argument('-l', '--link', action = 'store_true', help = 'Embed the munged string into a mailto: link')
args = parser.parse_args()

def mung(plain):
    munged = ''
    for c in plain:
        munged = munged + '&#' + str(ord(c)) + ';'
    return munged

string_munged = mung(args.string_to_mung)

if (args.link):
    print('<a href="&#109;&#97;&#105;&#108;&#116;&#111;&#58;')
    print(string_munged + '">')
    print(string_munged + '</a>')
  • 1
    \$\begingroup\$ Spam bots deal rather well with X(HT)ML escape sequences since they often use appropriate parser libraries. \$\endgroup\$ Oct 8, 2018 at 8:53
  • \$\begingroup\$ Actually my experience suggests otherwise, as an obfuscated email address gets ten times less spam; see bit.ly/2UOuAOA \$\endgroup\$
    – dr_
    Dec 15, 2018 at 15:23

1 Answer 1


The code is straightforward and reads well, but:

  1. string concatenation is not very efficient, especially in a loop. You'd be better off using str.join on an iterable;
  2. encoding the mailto: part yourself impairs readability and maintenance, if only you had a function to do it for you. Oh wait...
  3. The comment at the beginning would be better as a module docstrings, you would then be able to use it as the argparse description using __doc__;
  4. You should avoid interleaving code and function definition, and protect top level code using an if __name__ == '__main__': guard.

Proposed improvements:


"""Convert a string into its HTML entities"""

import argparse

def command_line_parser():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('string_to_mung', help='String to convert')
    parser.add_argument('-l', '--link', action='store_true',
                        help='Embed the munged string into a mailto: link')
    return parser

def mung(plain):
    return ''.join('&#{};'.format(ord(c)) for c in plain)

if __name__ == '__main__':
    args = command_line_parser().parse_args()
    string_munged = mung(args.string_to_mung)
    if (args.link):
        string_munged = '<a href="{0}{1}">{1}</a>'.format(mung('mailto:'), string_munged)
  • \$\begingroup\$ Python 3.6+: '&#{};'.format(ord(c))f'&#{ord(c)};' \$\endgroup\$ Oct 7, 2018 at 22:55
  • 2
    \$\begingroup\$ @RomanOdaisky Given that there is no version tag, I prefer to keep format. \$\endgroup\$ Oct 7, 2018 at 23:20

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