全局变量的未绑定本地错误

Question

我试图弄清楚为什么我的pygame应用程序Table Wars中出现UnboundLocalError.以下是发生的情况摘要:

变量,REDGOLD,REDCOMMAND,BLUEGOLD和BLUECOMMAND,被初始化为全局变量:

#Red Stat Section
REDGOLD = 50
REDCOMMAND = 100
#Blue Stat Section
BLUEGOLD = 50
BLUECOMMAND = 100

def main():    

    [...]

    global REDGOLD
    global REDCOMMAND
    global BLUEGOLD
    global BLUECOMMAND

这在主循环中产生单位时减少了产生单位的资金.

现在,我正在尝试建立一个系统,以便当一个单位死亡时,杀手会根据他杀死的内容退还受害者COMMAND并获得收入GOLD:

class Red_Infantry(pygame.sprite.Sprite):
def __init__(self, screen):
    [...]
    self.reward = 15
    self.cmdback = 5

[...]

def attack(self):
    if self.target is None: return
    if self.target.health <= 0:
        REDGOLD += self.target.reward          #These are the problem lines
        BLUECOMMAND += self.target.cmdback     #They will cause the UnboundLocalError
                                               #when performed
        self.target = None
    if not self.cooldown_ready(): return
    self.target.health -= self.attack_damage
    print "Target's health: %d" % self.target.health

这一直有效直到装置死亡.然后这发生了:

Traceback (most recent call last):
File "C:\Users\Oventoaster\Desktop\Games\Table Wars\Table Wars.py", line 606, in <module>
main()
File "C:\Users\Oventoaster\Desktop\Games\Table Wars\Table Wars.py", line 123, in main
RedTeam.update()
File "C:\Python27\lib\site-packages\pygame\sprite.py", line 399, in update
for s in self.sprites(): s.update(*args)
File "C:\Users\Oventoaster\Desktop\Games\Table Wars\Table Wars.py", line 304, in update
self.attack()
File "C:\Users\Oventoaster\Desktop\Games\Table Wars\Table Wars.py", line 320, in attack
REDGOLD += self.target.reward
UnboundLocalError: local variable 'REDGOLD' referenced before assignment

如何通过attack块更改上面提到的全局变量？如果它有帮助,我使用Pygame 2.7.x,所以nonlocal不会工作:/

Answer 1

global使全局变量在当前代码块中可见.你只把global声明放入main,而不是放入attack.

附录

以下是不止一次使用全球需求的说明.试试这个:

RED=1

def main():
    global RED
    RED += 1
    print RED
    f()

def f():
    #global RED
    RED += 1
    print RED

main()

你会得到错误UnboundLocalError: local variable 'RED' referenced before assignment.

现在取消注释f中的全局语句,它将起作用.

该global声明在LEXICAL中有效,而不是DYNAMIC范围.

Answer 2

您需要在修改变量的每个范围内将变量声明为全局变量

最好找到一种不使用全局变量的方法。例如，将它们作为类属性有意义吗？