Dive Part 4 Oop High Quality - Python 3 Deep

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.

class A: def show(self): print("A") class B(A): def show(self): print("B") super().show() # Works, but rigid :

class BadCircle: def __init__(self, radius): self._radius = radius def get_radius(self): return self._radius def set_radius(self, value): if value < 0: raise ValueError("Radius cannot be negative") self._radius = value :

class Movable: def move(self): pass class Flyable: def fly(self): pass

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

: Do not overuse __ (double underscore). It breaks subclassing. Use _ for internal attributes and trust other developers. Python is a "consenting adults" language. 5. Inheritance Done Right: Composition over Inheritance Inheritance is overused. The Gang of Four principle: Favor object composition over class inheritance .