book_chapter3.txt

Ok, now lets look at what will happen when we add some networking code. 
We're writing a multiplayer game after all.

Imagine this was a 2-player game, opponents are connected to each other over
the internet, and when your opponent has a higher score than you, it makes
your monkey move faster.

It might look something like this:

----

def handle_events(clock):
    monkeys = []
    for sprite in sprites:
        if isinstance(sprite, Monkey):
            monkeys.append(sprite)

    for event in pygame.event.get():
        if event.type == c.QUIT:
            return False
        elif event.type == c.MOUSEBUTTONDOWN:
            for monkey in monkeys:
                monkey.attempt_punch(event.pos)

    opponentScore = get_opponent_score()
    difference = opponentScore - score
    if difference > 0:
        multiplier = 1.0 + difference/10.0
    else:
        multiplier = 1.0
    for monkey in monkeys:
        monkey.adjust_speed(multiplier)

    clock.tick(60) # aim for 60 frames per second
    for sprite in sprites:
        sprite.update()

    return True

----

This won't work.  An important fact to understand about sending and receiving
information over the network is that the network is slow. (Even "high speed"
networks still experience latency) Our screen won't be
redrawn every 1/60th of a second if it takes get_opponent_score() 2 seconds to
make a connection and pull down an integer from a remote host.

As proof, try to run this example with the networking functions simulated by
a sleep() of between 0 and 1 seconds.

----
----

As you can see, the monkey randomly jerks his way across the screen.  Bad monkey.

What do we do about these two opposing needs?  The display needs to be updated
many times per second, but networking calls can take seconds to return.