Python 3 Deep Dive Part 4 Oop High Quality Guide

ABCs are essential for large systems to enforce Liskov substitution. Descriptors are the mechanism behind @property , @classmethod , and @staticmethod . A descriptor is any class implementing __get__ , __set__ , or __delete__ .

: Register virtual subclasses.

class ValidateMixin: def process(self): print("Validating") super().process() python 3 deep dive part 4 oop high quality

order = Order() order.quantity = 10 # Works ABCs are essential for large systems to enforce

class PositiveNumber: def __set_name__(self, owner, name): self.name = name def __get__(self, instance, owner): if instance is None: return self return instance.__dict__.get(self.name) : Register virtual subclasses

Overriding __new__ allows you to control instance creation (e.g., caching, pooling, immutables). Never mutate __new__ without good reason, but understand it. 3. Properties vs. Getters/Setters – The Pythonic Way In languages like Java, private attributes are accessed via getters/setters. In Python, we start with public attributes and refactor to properties when needed.

from abc import ABC, abstractmethod class Stream(ABC): @abstractmethod def read(self): pass