Book Image

Mastering Python

By : Rick van Hattem
Book Image

Mastering Python

By: Rick van Hattem

Overview of this book

Python is a dynamic programming language. It is known for its high readability and hence it is often the first language learned by new programmers. Python being multi-paradigm, it can be used to achieve the same thing in different ways and it is compatible across different platforms. Even if you find writing Python code easy, writing code that is efficient, easy to maintain, and reuse is not so straightforward. This book is an authoritative guide that will help you learn new advanced methods in a clear and contextualised way. It starts off by creating a project-specific environment using venv, introducing you to different Pythonic syntax and common pitfalls before moving on to cover the functional features in Python. It covers how to create different decorators, generators, and metaclasses. It also introduces you to functools.wraps and coroutines and how they work. Later on you will learn to use asyncio module for asynchronous clients and servers. You will also get familiar with different testing systems such as py.test, doctest, and unittest, and debugging tools such as Python debugger and faulthandler. You will learn to optimize application performance so that it works efficiently across multiple machines and Python versions. Finally, it will teach you how to access C functions with a simple Python call. By the end of the book, you will be able to write more advanced scripts and take on bigger challenges.
Table of Contents (22 chapters)
Mastering Python
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
6
Generators and Coroutines – Infinity, One Step at a Time
Index

Logging


The Python logging module is one of those modules that are extremely useful, but it tends to be very difficult to use correctly. The result is often that people just disable logging completely and use print statements instead. This is insightful but a waste of the very extensive logging system in Python. If you've written Java code before, you might be familiar with the Log4j Java library. The Python logging module is largely and primarily based on that library.

The most important objects of the logging module are the following:

  • Logger: the actual logging interface

  • Handler: This processes the log statements and outputs them

  • Formatter: This formats the input data into a string

  • Filter: This allows filtering of certain messages

Within these objects, you can set the logging levels to one of the default levels:

  • CRITICAL: 50

  • ERROR: 40

  • WARNING: 30

  • INFO: 20

  • DEBUG: 10

  • NOTSET: 0

The numbers are the numeric values of these log levels. While you can generally ignore them, the order is obviously...