Python 3 Deep Dive Part 4 Oop High Quality

class Animal: def move(self): pass class Bird(Animal): def fly(self): pass class Penguin(Bird): # Penguins can't fly! Violates LSP pass

class A: pass class B(A): pass class C(A): pass class D(B, C): pass print(D.__mro__) # Output: ( , , , , ) Use code with caution. The Role of super()

stripe_gateway = StripePaymentGateway() paypal_gateway = PayPalPaymentGateway() python 3 deep dive part 4 oop high quality

for strict control over instance creation mechanics and working with immutable types.

class StrictDocstringMeta(type): def __new__(cls, name, bases, dct): # Intercept class creation if not dct.get('__doc__'): raise TypeError(f"Class '{name}' must have a docstring documentation.") return super().__new__(cls, name, bases, dct) # This works perfectly: class ValidClass(metaclass=StrictDocstringMeta): """This class is correctly documented.""" pass # This throws a TypeError immediately during module import: # class InvalidClass(metaclass=StrictDocstringMeta): # pass Use code with caution. 5. Pythonic Design Patterns class Animal: def move(self): pass class Bird(Animal): def

to make custom classes blend seamlessly with native Python syntax.

class ValidatedPositiveNumber: def __set_name__(self, owner, name): self.private_name = f"_{name}" def __get__(self, instance, objtype=None): if instance is None: return self return getattr(instance, self.private_name, 0) def __set__(self, instance, value): if value < 0: raise ValueError("Value must be positive") setattr(instance, self.private_name, value) class InventoryItem: price = ValidatedPositiveNumber() quantity = ValidatedPositiveNumber() def __init__(self, name: str, price: float, quantity: int): self.name = name self.price = price self.quantity = quantity Use code with caution. 3. Metaprogramming and Metaclasses class ValidatedPositiveNumber: def __set_name__(self

Whether you pursue formal coursework, self-study through documentation and tutorials, or a combination of both, the principles outlined in this article provide the roadmap. Python's OOP capabilities are rich and flexible; mastering them transforms you from a Python user into a Python craftsman.