Book Image

Expert Python Programming - Fourth Edition

By : Michał Jaworski, Tarek Ziadé
Book Image

Expert Python Programming - Fourth Edition

By: Michał Jaworski, Tarek Ziadé

Overview of this book

This new edition of Expert Python Programming provides you with a thorough understanding of the process of building and maintaining Python apps. Complete with best practices, useful tools, and standards implemented by professional Python developers, this fourth edition has been extensively updated. Throughout this book, you’ll get acquainted with the latest Python improvements, syntax elements, and interesting tools to boost your development efficiency. The initial few chapters will allow experienced programmers coming from different languages to transition to the Python ecosystem. You will explore common software design patterns and various programming methodologies, such as event-driven programming, concurrency, and metaprogramming. You will also go through complex code examples and try to solve meaningful problems by bridging Python with C and C++, writing extensions that benefit from the strengths of multiple languages. Finally, you will understand the complete lifetime of any application after it goes live, including packaging and testing automation. By the end of this book, you will have gained actionable Python programming insights that will help you effectively solve challenging problems.
Table of Contents (16 chapters)
14
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15
Index

Intercepting the class instance creation process

There are two special methods concerned with the class instance creation and initialization process. These are __init__() and __new__().

The __init__() method is the closest to the concept of the constructor found in many object-oriented programming languages. It receives a fresh class instance together with initialization arguments and is responsible for initializing the class instance state.

The special method __new__() is a static method that is actually responsible for creating class instances. This __new__(cls, [,...]) method is called prior to the __init__() initialization method. Typically, the implementation of the overridden __new__() method invokes its superclass version using super().__new__() with suitable arguments and modifies the instance before returning it.

The __new__() method is a special-cased static method so there is no need to declare it as a static method using the staticmethod decorator...