A different way to main()

import sys
import getopt

class Usage(Exception):
    def __init__(self, msg):
        self.msg = msg

def main(argv=None):
    if argv is None:
        argv = sys.argv
    try:
        try:
            opts, args = getopt.getopt(argv[1:], "h", ["help"])
        except getopt.error, msg:
             raise Usage(msg)
        # more code, unchanged
    except Usage, err:
        print >>sys.stderr, err.msg
        print >>sys.stderr, "for help use --help"
        return 2

if __name__ == "__main__":
    sys.exit(main())

What is this, you wonder? As it turns out, it’s Guido van Rossum’s preferred way to enter a Python program. It’s a sensible departure from the classic variant. Even though this post is from 2003, I am discovering for the first time; perhaps I will adopt this idiom in some of my programs since it has been blessed by the lord of Python.