When creating thousands of instances, the __slots__ directive optimizes memory usage. It instructs Python to bypass the instance dictionary and allocate a fixed-size array for attributes.
def __set__(self, obj, value): if not isinstance(value, str): raise TypeError(f"self.name must be a string") obj.__dict__[self.name] = value
class OptimisedPoint: __slots__ = ('x', 'y') def __init__(self, x, y): self.x = x self.y = y Use code with caution. Side Effects of __slots__
s = Secret() print(s._Secret__private) # Accessible via mangled name # print(s.__private) # AttributeError python 3 deep dive part 4 oop high quality
Inheritance allows classes to share behavior, while composition allows objects to contain other objects.
Object-Oriented Programming (OOP) is a foundational paradigm in Python, and understanding it at a deep level is essential for writing robust, scalable, and maintainable applications. In this article, we will go on a "deep dive" into the advanced concepts of OOP in Python 3, going far beyond simple class creation to explore the mechanics of the Python data model, descriptors, and metaprogramming. 1. The Foundation: Classes and Instances
When calling D() , the initialization trace prints in a nested fashion: Side Effects of __slots__ s = Secret() print(s
from abc import ABC, abstractmethod class DatabaseConnector(ABC): @abstractmethod def connect(self) -> bool: pass class PostgresConnector(DatabaseConnector): def connect(self) -> bool: return True # Instantiation succeeds Use code with caution. Structural Typing with typing.Protocol (Static Analysis)
def say_hello(): print("Hello")
Almost always. Class decorators and __init_subclass__ (Python 3.6+) solve 99% of metaclass use cases more simply. value): if not isinstance(value
class NonEmptyString(Validator): def validate(self, value): if not isinstance(value, str) or len(value.strip()) == 0: raise ValueError(f"self.name must be non-empty string")
Python supports multiple inheritance. Unlike C++, Python resolves method conflicts with the . Access it via ClassName.__mro__ .
A class acts as a blueprint, containing both data (attributes) and behavior (methods). Use code with caution.