logging-fstring-interpolation / W1203

Message emitted:

Use %s formatting in logging functions

Description:

Used when a logging statement has a call form of "logging.<logging method>(f"...")".Use another type of string formatting instead. You can use % formatting but leave interpolation to the logging function by passing the parameters as arguments. If logging-format-interpolation is disabled then you can use str.format. If logging-not-lazy is disabled then you can use % formatting as normal.

Problematic code:

import logging
import sys

logging.error(f"Python version: {sys.version}")  # [logging-fstring-interpolation]

Correct code:

import logging
import sys

logging.error("Python version: %s", sys.version)

Additional details:

This message permits to allow f-string in logging and still be warned of logging-format-interpolation.

Related links:

• logging variable data

• Rationale

Created by the logging checker.