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OOP & classes

Classes, instances, methods, dataclasses, and object-oriented design in Python.

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OOP & classes easy

How to Create Immutable Data Classes with frozen=True in Python

Create immutable data classes in Python using @dataclass(frozen=True) to prevent attribute modifications after instantiation.

dataclass frozen immutable
Python 
from dataclasses import dataclass

@dataclass(frozen=True)
class Point:
    x: float
    y: float

    def distance_from_origin(self) -> float:
        return (self.x**2 + self.y**2) ** 0.5

if __name__ == "__main__":
    p = Point(3.0, 4.0)
    print(p)
    print(f"Distance from origin: {p.distance_from_origin():.2f}…
13 0 Open
OOP & classes medium

How to Use __slots__ in Python Classes for Memory Efficiency

Defines classes with __slots__ to prevent dynamic attribute creation and reduce memory usage, including inheritance with additional slots.

slots oop memory
Python 
```python
class Person:
    __slots__ = ("name", "age")

    def __init__(self, name: str, age: int):
        self.name = name
        self.age = age

    def greet(self) -> str:
        return f"Hi, I'm {self.name} and I'm {self.age} years old."


class Employee(Person):
    __slots__ = ("role",)

    def __init__(se…
13 0 Open
OOP & classes medium

Observer Pattern in Python: Notify Listeners

Implement the Observer design pattern in Python with a Subject class that manages listeners and notifies them with messages.

design-pattern observer oop
Python 
class Subject:
    def __init__(self):
        self._observers = []

    def attach(self, observer):
        self._observers.append(observer)

    def detach(self, observer):
        self._observers.remove(observer)

    def notify(self, message):
        for observer in self._observers:
            observer.update(me…
12 0 Open
OOP & classes easy

Slots Class: How to Reduce Memory Usage in Python

Use __slots__ to prevent dynamic attribute creation and reduce per-instance memory overhead, while keeping methods intact.

memory slots class
Python 
class SlotsDemo:
    __slots__ = ("name", "age", "email")

    def __init__(self, name, age, email):
        self.name = name
        self.age = age
        self.email = email

    def describe(self):
        return f"{self.name}, {self.age}, {self.email}"

if __name__ == "__main__":
    instance = SlotsDemo("Alice", …
12 0 Open

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