Python warning message output

Question

With this code:

#! /usr/bin/env python
# -*- coding: utf-8 -*-

import sys
import warnings

if sys.version_info[0] >= 3:
    ...
else:
    warnings.warn("Python 3.x is required!", RuntimeWarning)

And the else output I get is:

Warning (from warnings module):
  File "C:\Users\..., line 10
    warnings.warn("Python 3.x is required!", RuntimeWarning)
RuntimeWarning: Python 3.x is required!

Is there any way of getting rid of the first 3 lines of the output and only display "RuntimeWarning: Python 3.x is required!" ?

If you only want the last line to be outputed, why not print it? — Carles Mitjans
– Carles Mitjans, Commented Dec 21, 2016 at 18:35
have you tried warnings.showwarning = send_warnings_to_log? — Armen Babakanian
– Armen Babakanian, Commented Dec 21, 2016 at 18:38

Armen Babakanian · Accepted Answer · 2017-12-07 19:56:12Z

14

from https://pymotw.com/2/warnings/#stack-level-in-warnings

Stack Level in Warnings

You’ll notice that by default the warning message includes the source line that generated it, when available. It’s not all that useful to see the line of code with the actual warning message, though. Instead, you can tell warn() how far up the stack it has to go to find the line the called the function containing the warning. That way users of a deprecated function see where the function is called, instead of the implementation of the function.

# warnings_warn_stacklevel.py
import warnings

def old_function():
    warnings.warn(
        'old_function() is deprecated, use new_function() instead', 
        stacklevel=2)

def caller_of_old_function():
    old_function()

caller_of_old_function()

Notice that in this example warn() needs to go up the stack 2 levels, one for itself and one for old_function().

$ python warnings_warn_stacklevel.py

warnings_warn_stacklevel.py:18: UserWarning: old_function() is deprecated, use new_function() instead   old_function()

edited Dec 7, 2017 at 19:56

answered Dec 21, 2016 at 18:41

Armen Babakanian

2,4053 gold badges31 silver badges57 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

K. Leontis Over a year ago

Why when I am setting stacklevel=2 I am getting this error? 'File "C:\Users\...\Python\Python35\lib\idlelib\run.py", line 351 exec(code, self.locals)'

Collectives™ on Stack Overflow

Python warning message output

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related