Book Image

Modern Python Cookbook - Second Edition

By : Steven F. Lott
Book Image

Modern Python Cookbook - Second Edition

By: Steven F. Lott

Overview of this book

Python is the preferred choice of developers, engineers, data scientists, and hobbyists everywhere. It is a great language that can power your applications and provide great speed, safety, and scalability. It can be used for simple scripting or sophisticated web applications. By exposing Python as a series of simple recipes, this book gives you insight into specific language features in a particular context. Having a tangible context helps make the language or a given standard library feature easier to understand. This book comes with 133 recipes on the latest version of Python 3.8. The recipes will benefit everyone, from beginners just starting out with Python to experts. You'll not only learn Python programming concepts but also how to build complex applications. The recipes will touch upon all necessary Python concepts related to data structures, object oriented programming, functional programming, and statistical programming. You will get acquainted with the nuances of Python syntax and how to effectively take advantage of it. By the end of this Python book, you will be equipped with knowledge of testing, web services, configuration, and application integration tips and tricks. You will be armed with the knowledge of how to create applications with flexible logging, powerful configuration, command-line options, automated unit tests, and good documentation.
Table of Contents (18 chapters)
16
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17
Index

Saving intermediate results with the := "walrus"

Sometimes we'll have a complex condition where we want to preserve an expensive intermediate result for later use. Imagine a condition that involves a complex calculation; the cost of computing is high measured in time, or input-output, or memory, or network resource use. Resource use defines the cost of computation.

An example includes doing repetitive searches where the result of the search may be either a useful value or a sentinel value indicating that the target was not found. This is common in the Regular Expression (re) package where the match() method either returns a match object or a None object as a sentinel showing the pattern wasn't found. Once this computation is completed, we may have several uses for the result, and we emphatically do not want to perform the computation again.

This is an example where it can be helpful to assign a name to the value of an expression. We&apos...