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

Parsing arguments


When writing command-line tools, it's usually common to have it change behavior based on options provided to the executable. These options are usually available in sys.argv together with the executable name, but parsing them is not as easy as it might seem, especially when multiple arguments must be supported. Also, when an option is malformed, it's usually a good idea to provide a usage message to inform the user about the right way to use the tool.

How to do it...

Perform the following steps for this recipe:

  1. The argparse.ArgumentParser object is the primary object in charge of parsing command-line options:
import argparse
import operator
import logging
import functools

parser = argparse.ArgumentParser(
    description='Applies an operation to one or more numbers'
)
parser.add_argument("number", 
                    help="One or more numbers to perform an operation on.",
                    nargs='+', type=int)
parser.add_argument('-o', '--operation', 
                  ...