How to implement the --verbose or -v option into a script?

Question

I know the --verbose or -v from several tools and I\'d like to implement this into some of my own scripts and tools.

I thought of placing:<

Answer 1

Use the logging module:

import logging as log
…
args = p.parse_args()
if args.verbose:
    log.basicConfig(format="%(levelname)s: %(message)s", level=log.DEBUG)
    log.info("Verbose output.")
else:
    log.basicConfig(format="%(levelname)s: %(message)s")

log.info("This should be verbose.")
log.warning("This is a warning.")
log.error("This is an error.")

All of these automatically go to stderr:

% python myprogram.py
WARNING: This is a warning.
ERROR: This is an error.

% python myprogram.py -v
INFO: Verbose output.
INFO: This should be verbose.
WARNING: This is a warning.
ERROR: This is an error.

For more info, see the Python Docs and the tutorials.