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

Creating contexts and context managers

A number of Python objects behave like context managers. Some of the most visible examples are file objects. We often use with path.open() as file: to process a file and guarantee the resources are released. In Chapter 2, Statements and Syntax, the recipe Context management and the "with" statement covers the basics of using a file-based context manager.

How can we create our own classes that act as context managers?

Getting ready

We'll look at a function from Chapter 3, Function Definitions, in the Picking an order for parameters based on partial functions recipe. This recipe introduced a function, haversine(), which has a context-like parameter used to adjust the answer from dimensionless radians to a useful unit of measure, such as kilometers, nautical miles, or US statute miles. In many ways, this distance factor is a kind of context, used to define the kinds of computations that are done.

What we want is to...