Singleton Pattern in C++: Understanding and Implementation

𝐃𝐞𝐬𝐢𝐠𝐧 𝐏𝐚𝐭𝐭𝐞𝐫𝐧𝐬 𝐟𝐨𝐫 𝐄𝐯𝐞𝐫𝐲 𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐞𝐫 𝐋𝐞𝐯𝐞𝐥 𝐉𝐮𝐧𝐢𝐨𝐫 → Write clean, flexible code (Builder, Factory, Singleton, Decorator) 𝐌𝐢𝐝→ Build scalable & modular systems (Strategy, Adapter, Facade, Command) 𝐒𝐞𝐧𝐢𝐨𝐫→ Handle complexity like a pro (Prototype, State, Proxy, Interpreter) Patterns aren’t just concepts — they’re your shortcut to writing better code faster. Follow Madhu K. for more coding & system design content #DesignPatterns #SoftwareEngineering #Java #SystemDesign #Coding

One design pattern that is very useful when object creation is expensive or repetitive is the 𝙋𝙧𝙤𝙩𝙤𝙩𝙮𝙥𝙚 𝙋𝙖𝙩𝙩𝙚𝙧𝙣. Its idea is simple: 𝒊𝒏𝒔𝒕𝒆𝒂𝒅 𝒐𝒇 𝒄𝒓𝒆𝒂𝒕𝒊𝒏𝒈 𝒂 𝒏𝒆𝒘 𝒐𝒃𝒋𝒆𝒄𝒕 𝒇𝒓𝒐𝒎 𝒔𝒄𝒓𝒂𝒕𝒄𝒉, 𝒚𝒐𝒖 𝒄𝒍𝒐𝒏𝒆 𝒂𝒏 𝒆𝒙𝒊𝒔𝒕𝒊𝒏𝒈 𝒐𝒏𝒆. This is helpful when an object contains many fields, complex configuration, or costly initialization logic. Rather than rebuilding the same structure again and again, you create a prototype once, then duplicate it when needed. Why it is useful: • it improves performance when creation is costly • it reduces repetitive initialization code • it helps create similar objects quickly • it is useful when object setup is complex A simple Java example: imagine a DocumentTemplate object with title, layout, theme, permissions, and metadata already configured. Instead of rebuilding every new document manually, you clone the template and then adjust only what is different. That means: • the prototype keeps the base configuration • the clone copies the existing state • the client modifies only the needed values This is the real value of the 𝙋𝙧𝙤𝙩𝙤𝙩𝙮𝙥𝙚 𝙋𝙖𝙩𝙩𝙚𝙧𝙣: reuse fully configured objects instead of recreating them from zero. It is especially useful in: • document templates • UI components • game objects • configuration-heavy models The 𝙋𝙧𝙤𝙩𝙤𝙩𝙮𝙥𝙚 𝙋𝙖𝙩𝙩𝙚𝙧𝙣 is a good reminder that sometimes the best way to create an object is not to build it, but to copy it intelligently. #Java #DesignPatterns #PrototypePattern #SoftwareEngineering #BackendDevelopment #OOP #CleanCode #Architecture

I actually really like seeing information like this. Proves more to me that engineering is a mindset and how you use the tools you have.

Stop debating Blueprints vs C++. Neither is your problem. Clair Obscur: Expedition 33 just shipped as one of 2025's best-reviewed games. 95% Blueprints. Even their programmers used Blueprints. Meanwhile, I've seen C++ projects run at 15fps because the devs followed "optimization advice" they read online. "Move your Ticks to Timers." Bullsh*t. Timers are just Tick with indirection. Tick isn't the devil. It's a tool. If your Tick is slow, there are a few possibilities: 1. It shouldn't be a Tick. Make it event-driven 2. Your code is sh*t 3. The work needs time-slicing across frames 4. Ticking thousands of sparse objects? Requires clever ticking or DOD/ECS That's it. But event-driven requires rethinking architecture. "My code is sh*t" requires opening a profiler. Time-slicing requires chunking work. DOD requires rethinking memory layout. All harder than dragging a Timer node, so people don't do them. I've looked at hundreds of UE projects. The bottleneck is almost never Blueprints vs C++. Almost never Tick vs Timer. It's developers optimizing by vibes instead of data. Clair Obscur shipped AAA on Blueprints. Valorant runs smooth on potato hardware. Cargo cult advice isn't the solution. Your profiler is. What's the worst "optimization tip" you've followed that actually hurt your project?

🚀 Day 3/25 — LLD Practice: Notification System (Design) Today I designed a scalable and extensible Notification System using multiple design patterns. 🧩 Functional Requirements: System should send notifications via multiple channels (Email, SMS, Popup) Notifications can be dynamically extended with additional data (timestamp, signature, etc.) Multiple components should be notified when an event occurs System should support adding new notification types without changing existing code ⚙️ Non-Functional Requirements: Scalable to handle large number of notifications Extensible (plug & play for new notification channels) Low latency for real-time updates Reliable delivery of notifications 💡 What I learned: Observer Pattern for notifying multiple components Strategy Pattern for handling different notification channels Decorator Pattern for dynamically adding features to notifications How to combine multiple design patterns in one system 🛠️ Design Highlights: Decoupled notification sending logic using Strategy Pattern Dynamic notification enrichment using Decorator Pattern Event-based updates using Observer Pattern Clean and extensible architecture 🙏 Thanks to CoderArmy Aditya Tandon for helping me understand LLD concepts clearly. 📂 GitHub: https://lnkd.in/dUZ_NyRy #LLD #SystemDesign #Java #DesignPatterns #ObserverPattern #StrategyPattern #DecoratorPattern #100DaysOfCode #coderarmy

🧠 15 Must-Know Design Patterns Every Developer Should Learn Design patterns aren’t just theory — they are proven solutions to recurring problems in software design. Mastering them can significantly improve your code structure, scalability, and interview performance 🚀 Here are 15 essential design patterns to level up your development skills: 🔹 Creational Patterns Singleton Factory Method Builder 🔹 Structural Patterns 4. Adapter 5. Decorator 6. Facade 7. Proxy 8. Composite 🔹 Behavioral Patterns 9. Observer 10. Strategy 11. Command 12. Iterator 13. State 14. Template Method 15. Chain of Responsibility 💡 These patterns help you write clean, maintainable, and flexible code — something every strong backend developer should aim for. 📚 If you're preparing for interviews or improving system design skills, exploring each of these patterns in depth is a game changer. 👉 Start learning with these resources: Singleton: https://lnkd.in/gGNe7TVM Factory Method: https://lnkd.in/gRypyrgG Builder: https://lnkd.in/gkdUad_v Adapter: https://lnkd.in/gm4GHWG4 Decorator: https://lnkd.in/gSQ6yBtU Facade: https://lnkd.in/g4k5ZKai Proxy: https://lnkd.in/g-qQcQbG Composite: https://lnkd.in/gvP6QMHg Observer: https://lnkd.in/gjcaR8UG Strategy: https://lnkd.in/g_Uux2CN Command: https://lnkd.in/gcH7BT7K Iterator: https://lnkd.in/gA4KJgAh State: https://lnkd.in/gGvv247K Template Method: https://lnkd.in/gGFxUuhR Chain of Responsibility: https://lnkd.in/gw_BFihR 💬 Save this post for quick revision and share it with someone preparing for tech interviews! #DesignPatterns #Java #SystemDesign #BackendDevelopment #SoftwareEngineering

🧩 Structural Design Patterns Structural Design Patterns focus on how classes and objects are organized to build flexible and maintainable systems. They help reduce tight coupling and make code easier to extend. Common Structural Patterns: Adapter → converts one interface to another Bridge → separates abstraction from implementation Composite → treats individual and group objects the same Decorator → adds behavior dynamically Facade → provides a simple interface to a complex system Proxy → controls access to an object Flyweight → saves memory by sharing common data Why does it matter? These patterns are heavily used in real-world Java applications for: legacy integration wrappers service orchestration logging/security file/folder structures 🎯 In short: Structural patterns help different parts of a system work together in a clean and scalable way. Interview One-Liner Structural Design Patterns deal with how classes and objects are composed to build flexible and maintainable structures while reducing tight coupling. #java #designpatterns #softwaredesign #backenddeveloper #springboot #programming

🚦 Designing a Traffic Light System — Using State Design Pattern Ever noticed how a traffic light smoothly changes from Red → Green → Yellow without confusion............... It looks simple, but behind the scenes, each color represents a different behavior. I recently built a mini version of this system in Java, and it turned into a great example of using the State Design Pattern effectively. 🧩 The Problem We have a traffic light with multiple states: 🔴 Red → Stop 🟢 Green → Go 🟡 Yellow → Slow down Now the challenge: 👉 The system should behave differently based on its current state 👉 And it should be easy to add new states like: Blinking (night mode) Maintenance mode ❌ The Naive Approach Most people start with: if (color.equals("RED")) { ... } else if (color.equals("GREEN")) { ... } else if (color.equals("YELLOW")) { ... } 🚫 Problems: Not scalable Becomes messy with more states Violates Open/Closed Principle Hard to maintain ✅ The Better Approach: State Design Pattern We shift from conditions → objects Instead of one class handling everything: 👉 Each state becomes its own class ⚙️ How It Works Step 1: Define a State Interface Each state defines what happens next Step 2: Create Separate State Classes RedState → decides next = Green GreenState → decides next = Yellow YellowState → decides next = Red Each state controls its own behavior 🔥 Step 3: Context Class (TrafficLight) 👉 Holds the current state 👉 Delegates behavior to that state 👉 The context doesn’t care how things work internally 🔥 Why This Design Wins ✅ Open/Closed Principle Add new modes without modifying old code ✅ High Cohesion Each class = one responsibility ✅ Low Coupling States don’t interfere with each other ✅ Cleaner Thinking You model real-world behavior naturally 🌍 Real-World Use Cases 🎬 Media players (Play, Pause, Stop) 🥤 Vending machines (NoCoin, HasCoin) 📄 Document workflows (Draft, Review, Published) 🎮 Game characters (Idle, Running, Attacking) 🚀 Interview Insight If you explain this well, you show: 1. Real understanding of design patterns 2. Ability to write scalable code 3. Strong problem-solving mindset #SystemDesign #Java #DesignPatterns #StatePattern #CleanCode #SoftwareEngineering #InterviewPrep

Too Many Constructor Dependencies? That’s Not a Spring Problem — That’s a Design Problem** I often hear this: > “Constructor injection becomes confusing when there are too many dependencies… so let’s use @Autowired or field injection.” Let’s pause there. 🚨 The Real Issue If your constructor looks like this: ```java public OrderService( PaymentService paymentService, InventoryService inventoryService, NotificationService notificationService, AuditService auditService, PricingService pricingService, DiscountService discountService ) { ... } ``` 👉 This is NOT an injection problem 👉 This is a **class doing too much** 🧠 What It Actually Means * Violating **Single Responsibility Principle** * High coupling * Hard to test * Hard to maintain * Low readability ❌ Common Misconception “Let’s switch to field injection using @Autowired to make it cleaner” ```java @Autowired private PaymentService paymentService; @Autowired private InventoryService inventoryService; ... ``` 👉 This only **hides the problem**, doesn’t solve it ✅ Better Approach * Break the class into smaller responsibilities * Introduce **facades or domain services** * Group related dependencies into cohesive units Example: ```java public OrderService(OrderProcessingFacade facade) { this.facade = facade; } ``` 🔍 About @Autowired * Not needed for constructor injection (Spring handles it automatically) * Not a solution for ambiguity * If multiple beans exist → use: * `@Qualifier` * `@Primary` 🔥 Engineering Insight > “When constructor injection feels heavy, > it’s your design asking for refactoring.” 🚀 Final Takeaway Don’t switch injection style to fix complexity. Fix the **design**. #SpringBoot #CleanCode #SoftwareArchitecture #Java #BackendEngineering #SystemDesign

Specs work well for coding logic where the requirements are known up front. E.g. bugs, tightly scoped improvements, known goals, etc. But they fail for code that emerges through discovery, because you cannot specify something that has an unknown ending. You can only see the next step in the journey. Iterative prompting helps with the latter but it's still not perfect. I like to work at two iterative abstraction layers, one code, one design, but it's a bit clunky. Are there any more programming "modes"? Or are these two really all there is?