关于python面向对象初探示例代码

import random

class Sprite:

 step = [-2,+2,-3,+3]

 def __init__(self,gm,point=None):
 self.gm = gm
 if point is None:
 self.point = random.randint(0,20)
 else:
 self.point = point

 def jump(self):
 astep = random.choice(Sprite.step)
 if 0 <= self.point + astep <= 20:
 self.point += astep

class Ant(Sprite):

 def __init__(self,gm,point=None):
 super().__init__(gm,point)
 self.gm.set_point('ant',self.point)

 def jump(self):
 super().jump()
 self.gm.set_point('ant',self.point)

class Worm(Sprite):

 def __init__(self,gm,point=None):
 super().__init__(gm,point)
 self.gm.set_point('worm',self.point)

 def jump(self):
 super().jump()
 self.gm.set_point('worm',self.point)

class GameMap:
 def __init__(self):
 self.ant_point = None
 self.worm_point = None

 def catched(self):
 print('ant:',self.ant_point,'worm:',self.worm_point)
 if self.ant_point is not None and self.worm_point is not None and self.ant_point == self.worm_point:
 return True

 def set_point(self,src,point):
 if src == 'ant':
 self.ant_point = point
 if src == 'worm':
 self.worm_point = point

if __name__ == '__main__':
 gm = GameMap()
 worm = Worm(gm)
 ant = Ant(gm)
 while not gm.catched():
 worm.jump()
 ant.jump()