multilevelformatter 0.3.5

logger.Formatter to simplify setting formatting for multiple logging levels

MultiLevelFormatter

MultiLevelFormatter is a Python logging.Formatter that simplifies setting log formats for different log levels. Log records with level logging.ERROR or higher are printed to STDERR if using defaults with MultilevelFormatter.setDefaults().

Importing MultiLevelFormatter adds MESSAGE level (25) to logging and an logging.message() method. The idea is that you can use logging.message() instead of print() and use logging levels to control verbosity. See the full example below.

Install

Python 3.11 or later is required.

pip install multilevelformatter

Usage

Please note. If you use mypy, you need to add # type: ignore to the lines assigning logging.message to message (function) and whenever using logging.MESSAGE log level name. In practice this will be few lines in a module. mypy does not recognize the modifications to the logging class that is done when importing multilevelformatter. See mypy#5363 for details.

logger = logging.getLogger(__name__)
error = logger.error
warning = logger.warning
# added when importing multilevelformatter
message = logging.message  # type: ignore 
verbose = logger.info
debug = logger.debug

# Not complete, does not run
def main() -> None:
    
    ...

    # assumes command line arguments have been parsed into 
    # boolean flags: arg_verbose, arg_debug, arg_silent
    
    # MultiLevelFormatter adds MESSAGE level (25) to logging
    LOG_LEVEL: int = logging.MESSAGE # type: ignore 
    if arg_verbose: 
        LOG_LEVEL = logging.INFO
    elif arg_warning:
        LOG_LEVEL = logging.WARNING
    elif arg_debug:
        LOG_LEVEL = logging.DEBUG
    elif arg_silent:
        LOG_LEVEL = logging.ERROR
    MultilevelFormatter.setDefaults(logger, log_file=log)
    logger.setLevel(LOG_LEVEL)

    ...

Example

Full runnable example below. It can be found in demos/ folder.

import logging
from typer import Typer, Option
from typing import Annotated, Optional
from pathlib import Path
from multilevelformatter import MultilevelFormatter

logger = logging.getLogger(__name__)
error = logger.error
# MultiLevelFormatter adds MESSAGE level and message() to logging
message =  logger.message # type: ignore 
verbose = logger.info
debug = logger.debug

# the demo uses typer for CLI parsing. 
# Typer has nothing to do with MultiLevelFormatter
app = Typer()

@app.callback(invoke_without_command=True)
def cli(
    print_verbose: Annotated[
        bool,
        Option(
            "--verbose",
            "-v",
            show_default=False,
            help="verbose logging",
        ),
    ] = False,
    print_debug: Annotated[
        bool,
        Option(
            "--debug",
            show_default=False,
            help="debug logging",
        ),
    ] = False,
    print_silent: Annotated[
        bool,
        Option(
            "--silent",
            show_default=False,
            help="silent logging",
        ),
    ] = False,
    log: Annotated[Optional[Path], Option(help="log to FILE", metavar="FILE")] = None,
) -> None:
    """MultilevelFormatter demo"""
    global logger

    try:
        LOG_LEVEL: int = logging.MESSAGE # type: ignore 
        if print_verbose:
            LOG_LEVEL = logging.INFO
        elif print_debug:
            LOG_LEVEL = logging.DEBUG
        elif print_silent:
            LOG_LEVEL = logging.ERROR
        MultilevelFormatter.setDefaults(logger, log_file=log)
        logger.setLevel(LOG_LEVEL)
    except Exception as err:
        error(f"{err}")
    message("standard")
    verbose("verbose")
    error("error")
    debug("debug")


if __name__ == "__main__":
    app()