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Secret Recipes of the Python Ninja

You're reading from   Secret Recipes of the Python Ninja Over 70 recipes that uncover powerful programming tactics in Python

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Product type Paperback
Published in May 2018
Publisher Packt
ISBN-13 9781788294874
Length 380 pages
Edition 1st Edition
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Author (1):
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Cody Jackson Cody Jackson
Author Profile Icon Cody Jackson
Cody Jackson
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Table of Contents (11) Chapters Close

Preface 1. Working with Python Modules FREE CHAPTER 2. Utilizing the Python Interpreter 3. Working with Decorators 4. Using Python Collections 5. Generators, Coroutines, and Parallel Processing 6. Working with Python's Math Module 7. Improving Python Performance with PyPy 8. Python Enhancement Proposals 9. Documenting with LyX 10. Other Books You May Enjoy

Implementing ChainMap

ChainMap is a dictionary-like class, used to create a single view of multiple mappings. It allows for quick linking between multiple mappings so they can all be considered as a single unit, which is useful when simulating nested scopes and when templating. This can be faster than creating a new dictionary and running update() calls repeatedly.

The command to create a ChainMap is as follows:

collections.ChainMap(*maps)

As usual, the *maps is simply a number of dictionaries or other map objects passed in to be combined into a single, updateable view. If no mappings are passed in, then an empty dictionary is created so the new chain has at least one mapping available to it.

The mappings themselves are contained, behind the scenes, within a list. The list is a public object and it can be accessed or updated via the maps attribute. When looking for a key, the...

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