确定变量是否为任何类的实例 [英] Determine if a variable is an instance of any class

问题描述

如何确定变量是否是Python 3中的实例?如果它具有 __ dict __ 属性，我认为它是一个实例.

How to determine if a variable is an instance in Python 3? I consider something to be an instance if it has __dict__ attribute.

示例:

is_instance_of_any_class(5)  # should return False
is_instance_of_any_class([2, 3])  # should return False

class A:
  pass

a = A()
is_instance_of_any_class(a)  # should return True

我已经看到有关使用 isinstance(x，type)或 inspect.isclass(x)的消息，但这对于类(A)来说为True，而不是实例.

I have seen messages about using isinstance(x, type) or inspect.isclass(x) but this would give True for the class (A), not the instance.

推荐答案

我认为您对此实例的理解是错误的，因为所有内容都是python中的对象，所以 5 是的对象类 int 和 [2,3] 是类 list 的对象，依此类推.

I think your understanding of what an instance is wrong here, since everything is an object in python, so 5 is an object of class int and [2,3] is an object of class list and so on.

isinstance(x，y)是可行的方法，但是如果要检查 x 是内置类的对象还是您自己的自定义类，则应该使用 hasattr(x，'__dict __').

isinstance(x, y) is the way to go if you just want to check if x is an object of y, but if you want to check if x is an object of builtin class or your own custom defined class then you should be checking the existence of __dict__ using hasattr(x, '__dict__').

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