OOP &amp; classes

class WalletAccount:
    def __init__(self, owner, balance=0.0):
        self.owner = owner
        self.balance = balance

    def deposit(self, amount):
        if amount <= 0:
            raise ValueError("Deposit must be positive")
        self.balance += amount
        return self.balance

    def withdraw(self, …

dataclasses oop derived-fields

Compute Derived Fields with @dataclass __post_init__ in Python

Compute derived fields like distance, area, and perimeter automatically in Python dataclasses using __post_init__ and field(init=False).

from dataclasses import dataclass, field
from math import sqrt


@dataclass
class Point:
    x: float
    y: float
    distance: float = field(init=False)

    def __post_init__(self):
        self.distance = sqrt(self.x ** 2 + self.y ** 2)


@dataclass
class Rectangle:
    width: float
    height: float
    area: flo…

12 0 Open

context-manager with-statement resource-management

How to Build a Context Manager Class in Python

Create a reusable context manager class that opens and automatically closes resources using the with statement.

class FileResource:
    def __init__(self, filename, mode='r'):
        self.filename = filename
        self.mode = mode
        self.file = None

    def __enter__(self):
        self.file = open(self.filename, self.mode)
        return self.file

    def __exit__(self, exc_type, exc_value, traceback):
        if se…

12 0 Open

How to Call a Parent Class init with super() in Python

Shows how to chain __init__ calls through a class hierarchy using super(), so each class sets its own attributes while reusing the parent's initialization logic.

oop inheritance super

class Animal:
    def __init__(self, name, species):
        self.name = name
        self.species = species
        print(f"Animal init: {self.name}, {self.species}")

class Mammal(Animal):
    def __init__(self, name, species, fur_color):
        super().__init__(name, species)
        self.fur_color = fur_color
   …

copy deepcopy shallow copy

How to Copy Class Instances in Python: Shallow vs Deep Copy

Use copy.copy and copy.deepcopy to clone class instances, showing how nested objects are shared or duplicated.

import copy


class Config:
    def __init__(self):
        self.settings = {"theme": "dark", "language": "en"}


if __name__ == "__main__":
    original = Config()

    shallow_copy = copy.copy(original)
    deep_copy = copy.deepcopy(original)

    shallow_copy.settings["theme"] = "light"
    deep_copy.settings["them…

How to Create Static Methods in a Python Class

Shows how to define and call static methods inside a class using @staticmethod, with utility functions that don't need instance or class state.

static-method oop class

class MathUtils:
    """Utility class demonstrating static methods."""
    
    @staticmethod
    def add(a, b):
        """Return the sum of two numbers."""
        return a + b
    
    @staticmethod
    def multiply(a, b):
        """Return the product of two numbers."""
        return a * b
    
    @staticmethod
…

14 0 Open

How to Use StrEnum with auto() in Python

Define string-valued enum members automatically by using StrEnum with the auto() helper, making each member's value its own uppercase name.

enum strenum auto

from enum import StrEnum, auto

class Color(StrEnum):
    RED = auto()
    GREEN = auto()
    BLUE = auto()

class Language(StrEnum):
    PYTHON = auto()
    JAVASCRIPT = auto()
    RUST = auto()

print(list(Color))
print(list(Language))

print(Color.RED == "RED")
print(Language.PYTHON == "PYTHON")

print(f"Color: {Co…

adapter design-pattern oop

Python Adapter Class: Wrap Legacy Interface

Convert a legacy system's interface into a modern one using the Adapter pattern in Python, translating method calls and data formats.

class LegacySystem:
    """Legacy interface - old method names and parameter format."""
    def query_employee_info(self, emp_id, emp_name):
        return f"Legacy: {emp_id} - {emp_name}"

    def update_employee_department(self, emp_id, department_code):
        return f"Legacy: Updated {emp_id} to dept {department_…