Python 3 - Second Edition

19.10    Inheriting Built-In Data Types

Because data types and classes were unified in Python 2.3, Python is object-oriented from the ground up. This means that basically everything you come across when using Python is an instance of some class. From the simple number to the classes[ 94 ] themselves, each object has its own attributes and methods.

In particular, it’s possible to inherit from built-in data types such as list or dict.

The following example implements a subclass of list that automatically sorts its elements after each change:

class SortedList(list):    def __init__(self, *args, **kwargs):        super().__init__(*args, **kwargs)        self.sort()     def __setitem__(self, key, value):        super().__setitem__(key, value)        self.sort()     def append(self