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

Determining the type of a file


When we receive a file from our users, it's frequently necessary to detect its type. Doing so through the filename without the need to actually read the data can be achieved through the mimetypes module.

How to do it...

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

  1. While the mimetypes module is not bullet proof, as it relies on the name of the file to detect the expected type, it's frequently enough to handle most common cases.
  2. Users will usually assign proper names to their files for their own benefit (especially Windows users, where the extension is vital for the proper working of the file), guessing the type with mimetypes.guess_type is often enough:
import mimetypes

def guess_file_type(filename):
    if not getattr(guess_file_type, 'initialised', False):
        mimetypes.init()
        guess_file_type.initialised = True
    file_type, encoding = mimetypes.guess_type(filename)
    return file_type
  1. We can call guess_file_type against any file to get...