How to get a full stack summary from a traceback.TracebackException

Python Help
1

Hi,
The docs say that a TracebackException’s stack attribute is a stack summary but it seems to be only a frame.

How can I get the stack from the tbe?
I would like to save a TracebackException object in one process and log a stack trace later in another.
The snippet below prints
tbe.stack=[<FrameSummary file /home/pete/src/xpack/t.py, line 5 in b>]
Similarly, traceback.TracebackException.from_exception(e).format() does not include function a; however traceback.format_stack() has both a and b.

I am not an expert on the python stack and exception machinery so probably I am missing something obvious. A solution or workaround would be greatly appreciated.
Thank you!!

import traceback

def b():
    try:
        1/0
    except Exception as e:
        tbe = traceback.TracebackException.from_exception(e)
        print(f'{tbe.stack=}')

def a():
    b()

a()
2

You are missing other stack frames, use extract_stack():

import traceback

def b():
    try:
        1/0
    except Exception as e:
        tbe = traceback.TracebackException.from_exception(e)
        stack_frames = traceback.extract_stack()
        tbe.stack.extend(stack_frames)
        formatted_traceback = ''.join(tbe.format())
        print(f'Formatted Traceback:\n{formatted_traceback}')

def a():
    b()

a()

It has been years since I used traceback to implement it in my system. That’s just how I did it back then; I used extract_stack() .

1 Like
3

Thanks for the info Elis; after a bit more digging I found an old blog post and a SO thread, and came up with this solution, which works for me and hopefully others may find useful.

import sys
import traceback

def b():
    try:
        1/0
    except Exception as e:
        tbe = traceback.TracebackException.from_exception(e)
        print(f"Local {''.join(tbe.format())}")
        f = sys.exc_info()[2].tb_frame
        f = f.f_back
        while f is not None:
            tbe.stack.append(traceback.FrameSummary(
                f.f_code.co_filename, f.f_lineno, f.f_code.co_name))
            f = f.f_back

        print()
        print(f"Full {''.join(tbe.format())}")

def a():
    b()

a()

Output:

$ python t.py
Local Traceback (most recent call last):
  File "/home/pete/src/xpack/t.py", line 6, in b
    1/0
    ~^~
ZeroDivisionError: division by zero


Full Traceback (most recent call last):
  File "/home/pete/src/xpack/t.py", line 6, in b
    1/0
    ~^~
  File "/home/pete/src/xpack/t.py", line 21, in a
    b()
  File "/home/pete/src/xpack/t.py", line 23, in <module>
    a()
ZeroDivisionError: division by zero

The SO post (which references the blog):

1 Like