如何追溯函数内引发异常的原因？

Question

（这是Python try/ except: Showing the Cause of the error after Displaying my Variables 帖子的后续问题。）

我有以下内容script.py：

import traceback


def process_string(s):
    """
    INPUT
    -----
    s:  string

        Must be convertable to a float

    OUTPUT
    ------
    x:  float
    """

    # validate that s is convertable to a float
    try:
        x = float(s)
        return x
    except ValueError:        
        print
        traceback.print_exc()


if __name__ == '__main__':

    a = process_string('0.25')
    b = process_string('t01')
    c = process_string('201')

执行后script.py，终端窗口中将打印以下消息：

Traceback (most recent call last):
  File "/home/user/Desktop/script.py", line 20, in process_string
    x = float(s)
ValueError: could not convert string to float: t01

请问是否有一种方法可以traceback.print_exc()在终端窗口中打印 if-main 中的哪条指令引发了 try-except 子句捕获的异常？

Answer 1

那这个呢？

import traceback


def process_string(s):
    """
    INPUT
    -----
    s:  string

        Must be convertible to a float

    OUTPUT
    ------
    x:  float
    """
    return float(s)



if __name__ == '__main__':
    try:
        a = process_string('0.25')
        b = process_string('t01')
        c = process_string('201')
    except ValueError:        
        print
        traceback.print_exc()