异常与异常()

Question

print(Exception is Exception())
print(Exception == Exception())
print(type(Exception))
print(type(Exception())

try:
    raise Exception
except Exception:
    print("Caught Exception with Exception")
try:
    raise Exception()
except Exception:
    print("Caught Exception() with Exception")
try:
    raise Exception
except Exception():
    print("Caught Exception with Exception()")
try:
    raise Exception()
except Exception():
    print("Caught Exception() with Exception()")

>>> False
>>> False
>>> type
>>> Exception

>>> Caught Exception with Exception
>>> Caught Exception() with Exception
>>> TypeError: catching classes that do not inherit from BaseException is not allowed
>>> TypeError: catching classes that do not inherit from BaseException is not allowed

什么时候会用一个而另一个呢？被调用的表单()是否有无法调用的用例？问题适用于任何例外，而不仅仅是Exception。

Answer 1

区别在于Exception是类型，Exception()是该类的实例。

因此，当引发异常时，引发该类的实例：

raise Exception("Something happened")

当您捕捉到异常时，您基本上是在说“这段代码将处理Exception类型的任何实例”：

try: 
    raise Exception("Something happened")
except Exception as e: 
    print ("Caught an exception:", e) 

这也是你在问题中看到错误的原因：

>>> TypeError: catching classes that do not inherit from BaseException is not allowed

不允许捕获非Exception的类型，而Exception()是Exception的实例，而不是派生类型。

也见this answer。