Simple Log

A simple Python module to allow for simple and straightforward logging from your application.

Installation

Install simple log using pip

$ pip install simple_log

Usage

We try and stay true to the name and make using this module as simple as possible. For the simplest case just use

>>> from simple_log import get_log
>>> my_log = get_log()
>>> my_log.info("This is an information message")
2016.11.10 22:21:51 INFO:: This is an information message
>>> my_log.error("This is an error message")
2016.11.10 22:22:12 ERROR:: This is an error message
>>> my_log.warning("This is a warning message")
2016.11.10 23:29:14 WARNING:: This is a warning message

If you want to have multiple logs just pass a name to get_log

>>> first_log = get_log("first")
>>> first_log.info("Information message to first log")
2016.11.10 22:27:30 INFO:: Information message to first log
>>> second_log = get_log('two')
>>> second_log.debug("This is a debug message")
2016.11.10 22:28:02 DEBUG:: This is a debug message

By default the logging level is set to INFO (the standard module defaults to WARNING). See the logging tutorial for information on logging levels. If you would like to change the logging level, for instance to display DEBUG messages use the setLevel method on your log object

>>> from simple_log import get_log
>>> my_log = get_log('test_log')
>>> my_log.debug('This is the first debug message')
...
>>> my_log.setLevel('test_log', 'DEBUG')
>>> my_log.debug('This is the second debug message')
2016.11.10 22:34:55 DEBUG:: This is the second debug message

If you would like your log messages written to a file as well as the screen use the add_file function

>>> from simple_log import get_log, add_file
>>> my_log = get_log('test_log')
>>> my_log.info('This is an information message')
2016.11.12 22:48:10 INFO:: This is an information message
>>> add_file('test_log', 'test_log.log')
>>> my_log.info('This is another information message')
2016.11.12 22:49:30 INFO:: This is another information message
>>> cat test_log.log
2016.11.12 22:49:30 INFO:: This is another information message

the add_file function tries to be clever and should work if you pass it either the name of a log that was created using get_log or if you pass in the log object itself.

>>> from simple_log import get_log, add_file
>>> my_log = get_log('test_log')
>>> add_file(my_log, 'test_log.log')
>>> my_log.info('Information message to file')
2016.11.23 19:54:10 INFO:: Information message to file
>>> cat test_log.log
2016.11.23 19:54:10 INFO:: Information message to file

Why?

Why should you use simple_log and not the Python standard library logging module? Because simple_log follows one of the most import tenets of The Zen of Python - “Simple is better than complex”.

This module allows you to produce resonably formatted log messages from your Python code in the simplest possible way. Import the module, create a log then write messages. To get the same effect with the standard logging modules takes this much boilerplate code:

import logging
MESSAGE_FORMAT = "%(asctime)s %(levelname)s:: %(message)s"
DATE_FORMAT="%Y.%m.%d %T"
logger = logging.getLogger(self.__name__)
logger.setLevel(logging.INFO)
formatter = logging.Formatter(MESSAGE_FORMAT, DATE_FORMAT)
ch = logging.StreamHandler()
ch.setFormatter(formatter)
logger.addHandler(ch)

If simple_log does nothing else it stops you repeating that code in every Python script that you write.

Code Structure

The only dependency for simple_log is the Python standard library logging module

This package is made up of one Python module called log_utilities.py within the simple_log module. It has two functions

simple_log.get_log(logname=None)

Return a log object called <logname>

If you don’t specify a <logname> your returned object will have the name default

Log objects returned by this function have a logging level of ‘INFO’ and a sensible message output format including the current date and time and then the log level followed by the log message.

simple_log.add_file(log_name, file_name)

Add a file handler to log messages directed to <log_name> to <file_name>

We can accept either a log object or the name of a log object in the <log_name> parameter