Python 3 Deep Dive Part 4 Oop High Quality [hot] Info

class User: def __init__(self, username, hashed_password): self.username = username self._hashed_password = hashed_password

To define interfaces and abstract behaviors in Python, you can choose between two main methodologies: Abstract Base Classes (nominal typing) and Protocols (structural typing). Nominal Typing with ABCs

class VerifyAPIContract(type): def __new__(mcs, name, bases, class_dict): # Intercept before the class is finalized if name != "BaseAPI" and "execute" not in class_dict: raise TypeError(f"Class 'name' must implement an 'execute' method.") # Enforce snake_case naming for methods for key in class_dict.keys(): if not key.startswith('__') and not key.islower(): raise NameError(f"Method 'key' in 'name' must use snake_case naming.") return super().__new__(mcs, name, bases, class_dict) Use code with caution. Enforcing the Rules python 3 deep dive part 4 oop high quality

A metaclass allows you to intercept the creation of a class, inspect its attributes, or modify its structure before the class is fully defined. You use a metaclass by inheriting from type .

class Car(Engine): def drive(self): self.start() You use a metaclass by inheriting from type

Manage complex hierarchies with super() and MRO. Polymorphism: Use consistent interfaces. Abstraction: Leverage abc module.

: Learners have access to comprehensive Jupyter Notebooks and a GitHub repository for practical application. Abstraction: Leverage abc module

Python's power lies in its , which allows your custom objects to behave like built-in types through special methods (also known as dunder methods or magic methods). Understanding __str__ vs __repr__

@classmethod def __subclasshook__(cls, C): # Allow duck typing: any class with draw() is a Drawable if any("draw" in B.__dict__ for B in C.__mro__): return True return NotImplemented

Python supports multiple inheritance, which creates structural complexity like the classic "Diamond Problem" (where class D inherits from B and C , which both inherit from A ).

Since Python 3.5+, typing and Protocol (PEP 544) bring static duck-typing to OOP.