class Base: def __init_subclass__(cls, **kwargs): super().__init_subclass__(**kwargs) print(f"Subclass cls.__name__ created")

The dynamic nature of __dict__ consumes significant memory. If you are creating millions of instances, you can optimize memory by using __slots__ . This tells Python to use a static array for attributes instead of a dynamic dictionary.

class A(Base): def work(self): print("A.work start") super().work() print("A.work end")

Python 3 Deep Dive Part 4: Mastering Object-Oriented Programming (OOP)

class OptimizedCoordinate: __slots__ = ('x', 'y', 'z') def __init__(self, x, y, z): self.x = x self.y = y self.z = z Use code with caution. High-Quality Implementation Rules for __slots__

This is how Django models and SQLAlchemy columns work under the hood.

Metaprogramming involves writing code that manipulates other code. In Python, this means creating classes dynamically. __new__ vs __init__

class Validator: def __set_name__(self, owner, name): self.name = name def __get__(self, obj, objtype=None): return obj.__dict__.get(self.name)

Object-oriented programming (OOP) is a foundational paradigm in Python that organizes code around objects — data structures that bundle state (attributes) and behavior (methods). This essay explores Python 3’s OOP features and idioms in depth: classes and instances, attribute lookup and descriptors, data model methods, inheritance and MRO, metaprogramming, composition vs inheritance, and practical design guidance for robust, maintainable Python code.

bundles data and methods within a single unit (a class) and protects internal state from unintended interference.

def __get__(self, instance, owner): if instance is None: return self return instance.__dict__.get(self.name)

Custom metaclasses intercept the creation of classes. This is highly useful for framework development, API enforcement, automatic registration, and validation at load time.

Python uses the to determine the order in which base classes are searched. You can inspect this order using ClassName.mro() . The super() Function

class A: def __init__(self): print("A init") super().__init__() # Essential for MRO flow

C().work()

~repack~ - Python 3 Deep Dive Part 4 Oop High Quality