chronogram.py

import sys
from optparse import OptionParser


def reader(filename):
    with open(filename) as f:
        while True:
            char = f.read(1)
            if char:
                yield char
            else:
                return


def main():
    usage = ('usage: %s filename.txt') % sys.argv[0]
    parser = OptionParser(usage=usage)

    (options, args) = parser.parse_args()
    if len(args) < 1:
        parser.print_help()
        return -1

    numerals = {
        'I': 1,
        'V': 5,
        'X': 10,
        'L': 50,
        'C': 100,
        'D': 500,
        'M': 1000
    }

    filename = args[0]
    sum = 0

    file = reader(filename)
    for char in file:
        if char.upper() in numerals:
            sum += numerals[char.upper()]

    print('Chronogram sum of file ' + filename + ': ' + str(sum))


if __name__ == '__main__':
    main()