Spawning an alien to chase the player

Question

I have just made a simple script which spawns an alien that chases the player. I want to move as much of the script into functions so as to minimize the amount of code, to make it run better when my game gets a lot bigger. I am new to functions and classes, and I want to know what can be turned into a class in another script and how to go about doing it. I do not want just code, I want to be able to understand what I'm doing with it as well.

import pygame, sys, random, time, math
from pygame.locals import *
pygame.init()
bifl = 'screeing.jpg'
milf = 'character.png'
alien = 'alien_1.png'
screen = pygame.display.set_mode((640, 480))
background = pygame.image.load(bifl).convert()
mouse_c = pygame.image.load(milf).convert_alpha()
nPc = pygame.image.load(alien).convert_alpha()
x, y = 0, 0
movex, movey = 0, 0
z, w = random.randint(10, 480), random.randint(10, 640)
movez, movew = 0, 0
while True:
 for event in pygame.event.get():
 if event.type == QUIT:
 pygame.quit()
 sys.exit()
 if event.type == KEYDOWN:
 if event.key == K_w:
 movey = - 4
 elif event.key == K_s:
 movey = + 4
 elif event.key == K_a:
 movex = - 4
 elif event.key == K_d:
 movex = + 4
 if event.type == KEYUP:
 if event.key == K_w:
 movey = 0
 elif event.key == K_s:
 movey = 0
 elif event.key == K_a:
 movex = 0
 elif event.key == K_d:
 movex = 0
 if w < x:
 movew =+ 0.4
 if w > x:
 movew =- 0.4
 if z < y:
 movez =+ 0.4
 if z > y:
 movez =- 0.4
 x += movex
 y += movey
 w += movew
 z += movez
 print('charecter pos: ' + str(x) + str(y))
 print('alien pos: ' + str(w) + str(z))
 chpos = x + y
 alpos = w + z
 print(alpos, chpos)
 if chpos == alpos:
 pygame.quit()
 sys.exit()
 screen.blit(background, (0, 0))
 screen.blit(mouse_c, (x, y))
 screen.blit(nPc, (w, z))
 pygame.display.update()

• Mathieu Guindon: Not into Python but if you can put a name on a concept and picture that concept having properties and/or exposing methods or functions, you have a candidate for a class. As for functions, they should be doing as little as possible, which makes them easier to name and reuse.

Answer 1

Long multiple choice decisions in python work well as dictionaries, rather than elifs.

def handle_event(event):
 OnKeyDown = {K_w:(0, 4), K_s:(0,-4), K_a:(-4, 0), K_d:(4,0)}
 OnKeyUp = {K_w:(False, True), K_s:(False, True), K_a:(True, False), K_d:(True, False)}
 if event.type == KEYUP:
 delta = OnKeyDown[event]
 movex += delta[0]
 movey += delta[1]
 elif event.type == KEYDOWN:
 delta = OnKeyUp[event]
 if delta[0]: movex = 0
 if delta[1]: movey = 0
 x += movex
 y += movey

• testing4theLOLs4theWIN3: this is very good, but what would sort of code would i need to use these funtions to make the player move
• theodox: This function would replace the core if/elif block in your code above. You could probably just replace that whole section with this function .

Answer 2

You can create a class called AlienGame(object).

1. Put all the initialization code in a def __init__ function.

2. Put all creation of characters in a def create_characters function.

3. Put the chase part of the code in a def chase_player function.

This segregation of your code will make it more readable.