In Python, how can I print the current call stack from within a method (for debugging purposes).
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.
import traceback
traceback.print_stack()
traceback.print_exc()
which gives you almost the same thing you would have gotten without the except
statement (and is also less coding than the accepted answer).
traceback.print_exc()
prints the stack trace for any exception that you might be handling - but this does not solve the original question, which is how to print the current stack ("where you are now" as opposed to "where your code was when the last exception went off, if any".)
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.
for those who need to print the call stack while using pdb, just do
(Pdb) where
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
where
?
(pdb)
just type where
and it will print the stack trace to the terminal.
breakpoint()
which obviates the need to import pdb.
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
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
Success story sharing
sys._current_frames()
. E.g. py_better_exchookdump_all_thread_tracebacks
does that (disclaimer: I wrote that).