如何检查是否在Python中实例化了一个类

问题描述

所以我试图编写一个函数来实例化一个类。 由于我正在遍历该函数，因此我需要一个条件，以便该函数仅在尚未完成该类的情况下实例化该类（否则，HP将在每个循环中都处于极限状态）。 我尝试过的事情：

class Fighter:
    def __init__(self):
        self.maxHP = 100
        self.HP = self.maxHP
        self.attack = 10

def before_fight():
    if fighterYOU == None:    #this is where I would like a condition that checks if fighterYOU is already instantiated. "None" does not work.
        fighterYOU = Fighter()
    fighterYOU.update()
    fight()

before_fight()
#...program continues

是否可以进行这样的检查？还是应该尝试将实例化移动到不会循环的其他地方？

解决方法

如果我理解正确，那么您将避免重新创建战斗机。为此，只需先将变量设置为None：

class Fighter:
    def __init__(self):
        self.maxHP = 100
        self.HP = self.maxHP
        self.attack = 10

def before_fight():
    if fighterYOU == None:    #this is where I would like a condition that checks if fighterYOU is already instantiated. "None" does not work.
        fighterYOU = Fighter()
    fighterYOU.update()
    fight()

fighterYOU = None   # default is None

before_fight()
#...program continues

,

Here是答案。 if isinstance(obj,MyClass):是您所需要的。