使用exec修改类中的全局变量

Question

我最近重构了一些代码以使用OOP，但我遇到了一个问题，即我无法完全获得全局变量、exec()或两者的组合。相关代码如下：

# invObject class. Has all properties of an inventory object.
class invObject:
def __init__(self, name, info, output, effect):
self.name = name # Used in menus.
self.info = info # Describes effect.
self.output = output # Printed on use.
self.effect = effect # Executed on use.
def printInfo(self): # Function for name and description.
return "{} - {}".format(self.name, self.info)
def use(self): # Function to use items. It's that easy.
global dodgeChance
global maxHp
global hp
global atk
exec(self.effect)
print(self.output) # Prints output. Also very simple.
print("{} {} {} {}".format(dodgeChance, maxHp, hp, atk)) # debugging
...
inventory[slot].use() # does not update values

基本概要：inventory[slot].use()应该调用对象的use()函数。use()应该执行存储在inventory[slot].effect中的代码。

调试行的输出不会更改任何内容，即使在函数内部也是如此。我已经试过把它做成return exec(self.effect)了，但没有用。print(self.output)确实有效。

编辑：这是一个可复制的最小示例，它包括运行所需的一切，而不仅仅是最重要的东西。

# Assign base stats
dodgeChance = 0
maxHp = int(input("Input maximum HP. > "))
hp = int(input("Input current HP. > "))
# invObject class. Has all properties of an inventory object.
class invObject:
def __init__(self, name, info, output, effect):
self.name = name # Used in menus.
self.info = info # Describes effect.
self.output = output # Printed on use.
self.effect = effect # Executed on use.
def printInfo(self): # Function for name and description.
return "{} - {}".format(self.name, self.info)
def use(self): # Function to use items. It's that easy.
global dodgeChance
global maxHp
global hp
global atk
exec(self.effect)
print(self.output) # Prints output. Also very simple.
print("{} {} {} {}".format(dodgeChance, maxHp, hp, atk)) # debugging
empty = invObject("None", "Vacant slot.", "There's nothing in that slot!", "")
apple = invObject("Apple", "Gives 20 health.", "Ate the apple. Gained 20 health.", "hp = hp + 20nif hp > maxHp: hp = maxHp")
drink = invObject("Drink", "Some kind of energy drink. Raises dodge chance to 75%.", "Drank the drink. Dodge chance is now 75%!", "dodgeChance = 75")
# Assign base inventory
inventory = [apple, drink, empty]
slot = int(input("Input slot number to use. ")) - 1
inventory[slot].use() # does not update values
# Show final stats
print("New HP value: " + str(hp))
print("Dodge chance: " + str(dodgeChance) + "%")
print()
print("Inventory contents:")
print("Slot 1: " + str(inventory[0].name))
print("Slot 2: " + str(inventory[1].name))
print("Slot 3: " + str(inventory[2].name))

编辑2：另一件事：如果我不使用exec((，代码就可以工作(例如，将其更改为hp+=20(。

Answer 1

exec()具有可选参数，用于提供全局和局部变量上下文。

但你没有提供。