如何在python中创建新线程？

Question

I'm building a game in python, and I want to create an event listener that checks for when the main character's hp is smaller or equal to 0, and then executes a game over function. In other languages (vb.net) i have achieved this by creating a new thread that continuously loops an if statement until the condition is met, then runs the game over code, then closes itself. How do you create/start/close threads in python? Also, is there a better way of doing this that is sitting right in front of me?

Answer 1

from threading import Thread

def my_function():
    while True:
        if player.lives < 5:
            do_stuff()

Thread(my_function).start()

However most of the times the games are developed following a frame-loop rule, with the following structure:

def my_game():
    should_continue = False
    while should_continue:
        should_continue = update_logic()
        update_graphics()

What you define in update_logic and update_graphics is up to you and the graphic library you're using (since you're using text, your function would just print text in your console), but some examples of the logic would be like this:

def update_logic():
    if player.lives < 5:
        return False
    # these are just examples, perhaps not valid in your game
    player.xdirection = 0
    player.ydirection = 0
    player.speed = 0
    player.hitting = False
    if player.damage_received_timer > 0:
        player.damage_received_timer -= 1
    if right_key_pressed:
        player.xdirection = 1
    if left_key_pressed:
        player.xdirection = -1
    if up_key_pressed:
        player.ydirection = -1
    if down_key_pressed:
        player.ydirection = +1
    if player.ydirection or player.xdirection:
        player.speed = 20
    if space_key_pressed:
        player.hitting = True
    # bla bla bla more logic
    return True

This does not make use of threads and using threads is most of the times a bad practice if multiple events occur. However in your text games, perhaps not so much elements are involved, so it's unlikely a race condition would occur. Be careful, however. I always prefer these loops instead of threads.