是否可以从刚刚引发异常的方法访问对象？

Question

例如这段代码：

def foo():
    x = 5
    raise

def bar():
    try:
        foo()
    except:
        # access x here

是否可以以某种方式访问​​ x ？谢谢。

Answer 1

根据您的用例，更明智的方法是创建自定义异常并为其提供数据：

class MyException(Exception):
    def __init__(self, x, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.x = x

def foo():
    x = 5
    raise MyException(x)

def bar():
    try:
        foo()
    except MyException as e:
        print(e.x)

如果您确实需要能够访问所有局部变量，则可以遍历异常的回溯以检索每个堆栈帧的局部变量。这是一个适合您的特定示例的简单示例：

def bar():
    try:
        foo()
    except Exception as e:  # BaseException if you want to catch *everything*
        frame = e.__traceback__.tb_next.tb_frame
        print(frame.f_locals["x"])

通常，下一帧不一定是引发异常的帧。您可以遍历直到到达该框架，如下所示：

import traceback

def bar():
    try:
        foo()
    except Exception as e:
        # Get the last frame yielded, which will be where the exception was raised.
        *_, (frame, _) = traceback.walk_tb(e.__traceback__)
        print(frame.f_locals["x"])