Book Image

Secret Recipes of the Python Ninja

Book Image

Secret Recipes of the Python Ninja

Overview of this book

This book covers the unexplored secrets of Python, delve into its depths, and uncover its mysteries. You’ll unearth secrets related to the implementation of the standard library, by looking at how modules actually work. You’ll understand the implementation of collections, decimals, and fraction modules. If you haven’t used decorators, coroutines, and generator functions much before, as you make your way through the recipes, you’ll learn what you’ve been missing out on. We’ll cover internal special methods in detail, so you understand what they are and how they can be used to improve the engineering decisions you make. Next, you’ll explore the CPython interpreter, which is a treasure trove of secret hacks that not many programmers are aware of. We’ll take you through the depths of the PyPy project, where you’ll come across several exciting ways that you can improve speed and concurrency. Finally, we’ll take time to explore the PEPs of the latest versions to discover some interesting hacks.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell
Foreword
Contributors
Preface
Index

Improving decimal numbers


Python's built-in decimal module provides improved support for fast, precise floating point calculations. Normal float types are based on binary objects; decimal floats are completely different. Specifically, it improves on the normal float type by doing the following:

  • Operating like people learned in school, rather than forcing people to conform to a new arithmetic paradigm.
  • Representing decimal values exactly, rather than having results such as the following:
  • Ensuring the exactness of decimal values is carried through calculations, preventing rounding errors from compounding.

  • Accounting for significant digits, for example, 1.20 + 2.10 = 3.20, not 3.2, and 1.20 * 1.30 = 1.5600.
  • Allowing for user-specified precision, up to 28 places. This is different from float, which is dependent upon the platform.
  • Normal, binary float types only have a small portion of their capabilities exposed to the user. Decimal floats expose all required parts of the standard, allowing full control...