Mastering Object-oriented Python

Part 1. Pythonic Classes via Special Methods

The _init_() Method

Integrating Seamlessly with Python – Basic Special Methods

Attribute Access, Properties, and Descriptors

The ABCs of Consistent Design

Using Callables and Contexts

Creating Containers and Collections

Creating Numbers

Decorators and Mixins – Cross-cutting Aspects

Pythonic Classes via Special Methods

Python exposes a great deal of its internal mechanisms through its special method names. The idea is pervasive throughout Python. A function such as len() will exploit the __len__() special method of a class.

What this means is that we have a tidy, universal public interface (len(x)) that works on any kind of class. Python's polymorphism is based in part on the way any class can implement a __len__() ...