gistfile1.py

import itertools as it
import pygame as pg

#IMAGE LOADING

#a list of all image names
image_names = ["EnemyMoverRed", "EnemyMoverBlue", "BossMoverRed"]

#Make a dict to hold the images so they're only loaded once.

#a dict comprehension, similar to using a for loop to add to a dictionary
IMAGES = {name: pg.image.load("{}.png".format(name)).convert() for name in image_names}


#SIMPLE ANIMATION: using itertools.cycle and a tick count

#Make a separate class that inherits from Enemy for each specific kind of enemy
class RegularEnemy(Enemy):
    images = [IMAGES["EnemyMoverRed"], IMAGES["EnemyMoverBlue"]]
    def __init__(self, pos):
        super(RegularEnemy, self).__init__(pos) #whatever args Enemy.__init__ needs    
        
        #create a cycle (an endless iterator)    
        self.image_cycle = it.cycle(images)
        self.image = next(self.image_cycle)
        self.ticks = 0
        
    def update(self):
        self.ticks += 1
        if self.ticks % 6 == 0:
            self.image = next(self.image_cycle)
        
    def draw(self, surface):
        surface.blit(self.image, self.rect)

        
        
#create an Enemy instance
enemy = RegularEnemy((50, 50))

#once per frame in main loop
for enemy in enemies:
    enemy.update()