python语法raise A, L有什么用？

Question

如果调用下面的代码，其中L是一个列表，L是如何使用的？

raise A, L

Answer 1

请注意，此语法仅在 Python 2 中可用。Python 3 具有 lib2to3/fixes/fix_raise.py

在其 2 对 3 翻译系统中，该系统以以下文档字符串开头，为您提供有关文档保持沉默 (AFAIK) 的提示：

Fixer for 'raise E, V, T'

raise         -> raise
raise E       -> raise E
raise E, V    -> raise E(V)
raise E, V, T -> raise E(V).with_traceback(T)
raise E, None, T -> raise E.with_traceback(T)

raise (((E, E'), E''), E'''), V -> raise E(V)
raise "foo", V, T               -> warns about string exceptions


CAVEATS:
1) "raise E, V" will be incorrectly translated if V is an exception
   instance. The correct Python 3 idiom is

        raise E from V

   but since we can't detect instance-hood by syntax alone and since
   any client code would have to be changed as well, we don't automate
   this.

归结起来就是raise FooException, [1, 2]等价于raise FooException([1, 2])；但你应该总是使用后者。

python语法raise A, L有什么用？

What's the use of python syntax raise A, L?

exception

raise

python-2.7