Print current call stack from a method in code

Question

In Python, how can I print the current call stack from within a method (for debugging purposes).

Asked By: oneself

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Answer 1

Here’s an example of getting the stack via the traceback module, and printing it:

import traceback

def f():
    g()

def g():
    for line in traceback.format_stack():
        print(line.strip())

f()

# Prints:
# File "so-stack.py", line 10, in <module>
#     f()
# File "so-stack.py", line 4, in f
#     g()
# File "so-stack.py", line 7, in g
#     for line in traceback.format_stack():

If you really only want to print the stack to stderr, you can use:

traceback.print_stack()

Or to print to stdout (useful if want to keep redirected output together), use:

traceback.print_stack(file=sys.stdout)

But getting it via traceback.format_stack() lets you do whatever you like with it.

Answered By: RichieHindle

Answer 2

import traceback
traceback.print_stack()

Answered By: Mark Roddy

Answer 3

inspect.stack() returns the current stack rather than the exception traceback:

import inspect
print inspect.stack()

See https://gist.github.com/FredLoney/5454553 for a log_stack utility function.

Answered By: Fred Loney

Answer 4

If you use python debugger, not only interactive probing of variables but you can get the call stack with the “where” command or “w”.

So at the top of your program

import pdb

Then in the code where you want to see what is happening

pdb.set_trace()

and you get dropped into a prompt

Answered By: Keir

Answer 5

Here’s a variation of @RichieHindle’s excellent answer which implements a decorator that can be selectively applied to functions as desired. Works with Python 2.7.14 and 3.6.4.

from __future__ import print_function
import functools
import traceback
import sys

INDENT = 4*' '

def stacktrace(func):
    @functools.wraps(func)
    def wrapped(*args, **kwds):
        # Get all but last line returned by traceback.format_stack()
        # which is the line below.
        callstack = 'n'.join([INDENT+line.strip() for line in traceback.format_stack()][:-1])
        print('{}() called:'.format(func.__name__))
        print(callstack)
        return func(*args, **kwds)

    return wrapped

@stacktrace
def test_func():
    return 42

print(test_func())

Output from sample:

test_func() called:
    File "stacktrace_decorator.py", line 28, in <module>
    print(test_func())
42

Answered By: martineau

Answer 6

Install Inspect-it

pip3 install inspect-it --user

Code

import inspect;print(*['{:40}| {}:{}n'.format(x.function, x.filename, x.lineno) for x in inspect.stack()])

you can Make a snippet of this line

it will show you a list of the function call stack with a filename and line number

list from start to where you put this line

Answered By: MohitGhodasara

Answer 7

for those who need to print the call stack while using pdb, just do

(Pdb) where

Answered By: mouserat

Print current call stack from a method in code

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