Print only the message on warnings

I'm issuing lots of warnings in a validator, and I'd like to suppress everything in stdout except the message that is supplied to warnings.warn().

I.e., now I see this:

./file.py:123: UserWarning: My looong warning message
some Python code

I'd like to see this:

My looong warning message

Edit 2: Overriding warnings.showwarning() turned out to work:

def _warning(
    message,
    category = UserWarning,
    filename = '',
    lineno = -1):
    print(message)
...
warnings.showwarning = _warning
warnings.warn('foo')

There is always monkeypatching:

import warnings

def custom_formatwarning(msg, *args, **kwargs):
    # ignore everything except the message
    return str(msg) + '\n'

warnings.formatwarning = custom_formatwarning
warnings.warn("achtung")

Monkeypatch warnings.showwarning() with your own custom function.

Use the logging module instead of warnings.

Here's what I'm doing to omit just the source code line. This is by and large as suggested by the documentation, but it was a bit of a struggle to figure out what exactly to change. (In particular, I tried in various ways to keep the source line out of showwarnings but couldn't get it to work the way I wanted.)

# Force warnings.warn() to omit the source code line in the message
formatwarning_orig = warnings.formatwarning
warnings.formatwarning = lambda message, category, filename, lineno, line=None: \
    formatwarning_orig(message, category, filename, lineno, line='')

Just passing line=None would cause Python to use filename and lineno to figure out a value for line automagically, but passing an empty string instead fixes that.

Print only the message on warnings

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