CODEWITHSUNDEEP
pythonpygame
I_keep_getting_downvoted
I_keep_getting_downvoted

Reputation: 100

How to add subclass to a sprite group in pygame

I have got a base class called 'Block', that has its sprite groups set to game.all_sprites and game.blocks. I have a 'ground' subclass inheriting from the block class, but I am unable to get the ground to change sprite groups. Does anyone know how to do this? Block class:

class Block(pygame.sprite.Sprite):
    def __init__(self, game, x, y, collidable=True):
        self.groups = game.all_sprites, game.blocks
        pygame.sprite.Sprite.__init__(self, self.groups)
        self.game = game
        self.image = pygame.Surface((SCALE, SCALE))
        self.rect = self.image.get_rect()
        self.x = x
        self.y = y
        self.collidable = collidable

    def update(self):
        self.rect.x = self.x * SCALE
        self.rect.y = self.y * SCALE

Ground class:

class Ground(Block):
    def __init__(self, game, x, y, collidable=False):
        self.groups = game.all_sprites, game.grounds
        Block.__init__(self, game, x, y, collidable)

Thanks!

Upvotes: 2

Views: 695

Answers (1)

sloth
sloth

Reputation: 101122

You could use a method that you can override to define the groups:

class Block(pygame.sprite.Sprite):
    def __init__(self, game, x, y, collidable=True):
        pygame.sprite.Sprite.__init__(self, self.get_groups(game))
        self.game = game
        ...

    def get_groups(self, game):
        return game.all_sprites, game.blocks


class Ground(Block):

    def __init__(self, game, x, y, collidable=False):
        Block.__init__(self, game, x, y, collidable)

    def get_groups(self, game):
        return game.all_sprites, game.grounds

or store the attribute names of the sprite groups as class attribute and look them up dynamically, like this:

class Block(pygame.sprite.Sprite):
    groups = ['all_sprites', 'blocks']

    def __init__(self, game, x, y, collidable=True):
        pygame.sprite.Sprite.__init__(self, (getattr(game, g) for g in self.groups))
        self.game = game
        ...


class Ground(Block):
    groups = ['all_sprites', 'grounds']

    def __init__(self, game, x, y, collidable=False):
        Block.__init__(self, game, x, y, collidable)

or pass the groups as parameter from the sub class to the parent class:

class Block(pygame.sprite.Sprite):
    def __init__(self, game, x, y, collidable=True, groups=None):
        pygame.sprite.Sprite.__init__(self, groups or (game.all_sprites, game.blocks))
        self.game = game
        ...


class Ground(Block):

    def __init__(self, game, x, y, collidable=False, groups=None):
        Block.__init__(self, game, x, y, collidable, groups or (game.all_sprites, game.grounds))

In fact, the possibilities are endless:

class Block(pygame.sprite.Sprite):
    def __init__(self, game, x, y, collidable=True):
        groups = game.all_sprites, getattr(game, self.__class__.__name__.lower() + 's')
        pygame.sprite.Sprite.__init__(self, groups)
        self.game = game
        ...

I would probably use option 3, because it's explicit and has no fancy clever parts involved.

Upvotes: 2

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