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System design patterns

Sharding, load balancing, CAP tradeoffs, and scaling patterns — interview and production ready.

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How to Implement a Factory Method by Type String in Python

A factory method maps a type string to a class, creating and returning the appropriate object instance while handling unknown types gracefully.

factory-pattern design-patterns oop

Python

class Animal:
    def speak(self):
        raise NotImplementedError


class Dog(Animal):
    def speak(self):
        return "Woof!"


class Cat(Animal):
    def speak(self):
        return "Meow!"


class AnimalFactory:
    @staticmethod
    def create(animal_type: str) -> Animal:
        animal_types = {
          …

14 0 Open

System design patterns easy

How to Take Periodic Snapshots of Aggregate State in Python

Build a Python class that accumulates values and periodically captures immutable snapshots of total, count, and average for later analysis.

aggregation snapshots state-management

Python

import time
import random
from collections import defaultdict


class SnapshotAggregator:
    def __init__(self):
        self.total = 0
        self.count = 0
        self.history = []

    def add(self, value):
        self.total += value
        self.count += 1

    def snapshot(self):
        avg = self.total / se…

13 0 Open

System design patterns easy

Python MVC Pattern Example (Model-View-Controller)

A minimal, runnable Model-View-Controller (MVC) example in pure Python that separates data, presentation, and logic.

mvc design-pattern architecture

Python

class Model:
    def __init__(self):
        self.data = {"title": "Initial Title", "content": "Initial Content"}

    def get_data(self):
        return self.data

    def update_data(self, title=None, content=None):
        if title:
            self.data["title"] = title
        if content:
            self.data["c…

15 0 Open

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