Half-Life "Half Life" Calculator

hlhl.py

"""Functions for calculating when the game Half-Life has been out for exactly
half of someone's life.
"""
import datetime

release_date = datetime.date(1998, 11, 19)

def for_birthdate(birth_date):
    """Given a person's date of birth, return the date on which Half-Life has
    been out for half of their life.
    """
    return release_date + (release_date - birth_date)

def birthdate_for_today():
    """Return someone's date of birth for which Half-Life has today been out
    for half of their life.
    """
    today = datetime.date.today()
    return release_date - (today - release_date)

hlhl_example.py

import datetime

import hlhl


def main():
    print "If someone were born on %s, then today," % hlhl.birthdate_for_today()
    print "Half-Life would have been out for exactly half of their life."
    print

    my_birthdate = datetime.date(1989, 3, 17)
    my_hlhl = hlhl.for_birthdate(my_birthdate)

    print "My birthdate:", my_birthdate
    print "My Half-Life \"half life\":", my_hlhl
    print "... missed it. :("


if __name__ == '__main__':
    main()