Formatted string passed to logging module PYL-W1203

Formatting the message manually before passing it to a logging call does unnecessary work if logging is disabled. Consider using the logging module's built-in formatting features to avoid that.

If your logging level is set to "WARNING", but the logging call is:

logging.debug("Data: %s", data)

In the above example, there will be no logging as the level debug is below warning. The conversion of the data object to a string will be skipped by the logging module resulting in improved performance.

logging.debug(f"Data: {data}")

In the code shown above, the conversion of the data object to a string will happen regardless of whether the message is logged or not (which is based on the log level).

Bad practice

import logging
import inspect
logging.basicConfig(level=logging.INFO)
logging.debug(f"Entered function {inspect.stack[0][3]}"))

Recommended

import logging
import inspect
logging.basicConfig(level=logging.INFO)
logging.debug("Entered function %s", inspect.stack[0][3])