Python编程从⼊门到实践---pygame精灵组python编程:从入门到实践第二版
初学Python，跟着书上的外星⼈项⽬，写了⼀下，碰到⼀个这样的问题：
AttributeError: 'Alien' object has no attribute 'add_internal'
到的原因是，精灵组⾥⾯只能添加精灵，不能添加其他的⾮精灵的类，这也是我在这⾥犯的错。将需要添加到精灵组的类，需要继承Sprite类，犯错代码块如下：
正确的是：
既然碰到了精灵组，那就放些相关的知识吧。
pygame.sprite的官⽹api
常⽤的sprite⽅法
sprites()
list of the Sprites this Group contains
sprites() -> sprite_list
Return a list of all the Sprites this group contains. You can also get an iterator from the group, but you cannot iterator over a Group while modifying it.
copy()
duplicate the Group
copy() -> Group
Creates a new Group with all the same Sprites as the original. If you have subclassed Group, the new object will have the same (sub-)class as the original. This only works if the derived class's constructor takes the same arguments as the Group class's.
add()
add Sprites to this Group
add(*sprites) -> None
Add any number of Sprites to this Group. This will only add Sprites that are not already members of the Group.
Each sprite argument can also be a iterator containing Sprites.
remove()
remove Sprites from the Group
remove(*sprites) -> None
Remove any number of Sprites from the Group. This will only remove Sprites that are already members of the Group.
Each sprite argument can also be a iterator containing Sprites.
has()
test if a Group contains Sprites
has(*sprites) -> None
Return True if the Group contains all of the given sprites. This is similar to using the "in" operator on the Group ("if sprite in group: ..."), which tests if a single Sprite belongs to a Group.
Each sprite argument can also be a iterator containing Sprites.
update()
call the update method on contained Sprites
update(*args) -> None
Calls the update() method on all Sprites in the Group. The base Sprite class has an update method that takes any number of arguments and does nothing. The arguments passed to Group.update() will be passed to each Sprite.
There is no way to get the return value from the Sprite.update() methods.
draw()
blit the Sprite images
draw(Surface) -> None
Draws the contained Sprites to the Surface argument. This uses the Sprite.image attribute for the so
urce surface,
for the position.
The Group does not keep sprites in any order, so the draw order is arbitrary.
clear()
draw a background over the Sprites
clear(Surface_dest, background) -> None
Erases the Sprites used in the last Group.draw() call. The destination Surface is cleared by filling the drawn Sprite positions with the background.
The background is usually a Surface image the same dimensions as the destination Surface. However, it can also be a callback function that takes two arguments; the destination Surface and an area to clear. The background callback function will be called several times each clear.
Here is an example callback that will clear the Sprites with solid red:
def clear_callback(surf, rect):
color = 255, 0, 0
surf.fill(color, rect)
empty()
remove all Sprites
empty() -> None
Removes all Sprites from this Group.