Python 3 Deep Dive Part 4 Oop _hot_ (FREE)

first: Watch the first ~1 hour of preview videos on Udemy to check if the teaching style clicks for you.

class Player: health = PositiveNumber("health") def (self, health): self.health = health

This per-instance dictionary is convenient but carries a memory and speed cost. For a deeper understanding of how Python resolves attribute lookups, we must first understand the .

class User: def greet(self): return "Hello" # Access through class print(User.greet) # Output: # Access through instance u = User() print(u.greet) # Output: > Use code with caution.

If classes are blueprints for objects, then metaclasses are blueprints for classes. A is an object that creates a class—it is a class factory in the same way a class is an object factory. By default, all classes in Python are instances of the type metaclass. python 3 deep dive part 4 oop

The Ultimate Guide to Python 3 Deep Dive: Part 4 — OOP Object-Oriented Programming (OOP) in Python is often introduced as a way to bundle data and behavior using classes and instances. However, beneath the surface of basic class definitions lies a powerful, dynamic object model. Python handles object creation, attribute resolution, and inheritance using specific internal mechanisms.

class Developer: language = "Python" def __init__(self, name): self.name = name dev = Developer("Alex") # Inspecting namespaces print(Developer.__dict__) # Contains 'language', '__init__', etc. print(dev.__dict__) # Contains Only 'name': 'Alex' Use code with caution.

p = Point(10, 20)

class Point: __slots__ = ('x', 'y') def __init__(self, x, y): self.x = x self.y = y first: Watch the first ~1 hour of preview

Here is a metaclass that enforces all class methods to have documentation strings:

class DatabaseConnection: _instance = None def __new__(cls, *args, **kwargs): if cls._instance is None: cls._instance = super().__new__(cls) return cls._instance def __init__(self, connection_string): # Warning: __init__ will still be called every time # unless handled explicitly. self.connection_string = connection_string Use code with caution. 2. Advanced Attribute Lookup and Descriptors

By default, Python instances store their attributes inside a dynamic dictionary ( __dict__ ). This allows flexibility but introduces memory overhead due to the nature of hash tables. How __slots__ Works

Python supports multiple inheritance. The complexity arises when multiple parents define the same method. Python solves this using the algorithm. class User: def greet(self): return "Hello" # Access

class A: pass class B(A): pass class C(A): pass class D(B, C): pass

You can intercept class creation by writing a custom metaclass. This allows you to enforce architectural rules, auto-register plugins, or modify class attributes at creation time.

Object-Oriented Programming (OOP) in Python 3 is not just about syntax; it is about understanding how the language handles objects under the hood. Python treats everything as an object, from integers to functions.