Book Image

Modern Python Standard Library Cookbook

By : Alessandro Molina
Book Image

Modern Python Standard Library Cookbook

By: Alessandro Molina

Overview of this book

The Python 3 Standard Library is a vast array of modules that you can use for developing various kinds of applications. It contains an exhaustive list of libraries, and this book will help you choose the best one to address specific programming problems in Python. The Modern Python Standard Library Cookbook begins with recipes on containers and data structures and guides you in performing effective text management in Python. You will find Python recipes for command-line operations, networking, filesystems and directories, and concurrent execution. You will learn about Python security essentials in Python and get to grips with various development tools for debugging, benchmarking, inspection, error reporting, and tracing. The book includes recipes to help you create graphical user interfaces for your application. You will learn to work with multimedia components and perform mathematical operations on date and time. The recipes will also show you how to deploy different searching and sorting algorithms on your data. By the end of the book, you will have acquired the skills needed to write clean code in Python and develop applications that meet your needs.
Table of Contents (21 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Context managers


Decorators can be used to ensure that something is executed when you enter and exit a function, but in some cases, you might want to ensure that something is always executed at the beginning and end of a block of code without having to move it to its own function or without rewriting those parts that should be executed every time.

Context managers exist to solve this need, factoring out code that you would have to rewrite over and over in place of try:except:finally: clauses.

The most common usage of context managers is probably the closing context manager, which ensures that files get closed once the developer is done working with them, but the standard library makes it easy to write new ones.

How to do it...

For this recipe, the following steps are to be performed:

  1. contextlib provides features related to context managers, contextlib.contextmanager can make it very easy to write context managers:
@contextlib.contextmanager
def logentrance():
    print('Enter')
    yield
    print...