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name: design-patterns-implementation description: > Apply appropriate design patterns (Singleton, Factory, Observer, Strategy, etc.) to solve architectural problems. Use when refactoring code architecture, implementing extensible systems, or following SOLID principles.

Design Patterns Implementation

Table of Contents

• Overview
• When to Use
• Quick Start
• Reference Guides
• Best Practices

Overview

Apply proven design patterns to create maintainable, extensible, and testable code architectures.

When to Use

• Solving common architectural problems
• Making code more maintainable and testable
• Implementing extensible plugin systems
• Decoupling components
• Following SOLID principles
• Code reviews identifying architectural issues

Quick Start

Minimal working example:

class DatabaseConnection {
  private static instance: DatabaseConnection;
  private connection: any;

  private constructor() {
    this.connection = this.createConnection();
  }

  public static getInstance(): DatabaseConnection {
    if (!DatabaseConnection.instance) {
      DatabaseConnection.instance = new DatabaseConnection();
    }
    return DatabaseConnection.instance;
  }

  private createConnection() {
    return {
      /* connection logic */
    };
  }
}

// Usage
const db1 = DatabaseConnection.getInstance();
const db2 = DatabaseConnection.getInstance();
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

| Guide | Contents | |---|---| | Singleton Pattern | Singleton Pattern | | Factory Pattern | Factory Pattern | | Observer Pattern | Observer Pattern | | Strategy Pattern | Strategy Pattern | | Decorator Pattern | Decorator Pattern | | Repository Pattern | Repository Pattern | | Dependency Injection | Dependency Injection |

Best Practices

✅ DO

• Choose patterns that solve actual problems
• Keep patterns simple and understandable
• Document why patterns were chosen
• Consider testability
• Follow SOLID principles
• Use dependency injection
• Prefer composition over inheritance

❌ DON'T

• Apply patterns without understanding them
• Over-engineer simple solutions
• Force patterns where they don't fit
• Create unnecessary abstraction layers
• Ignore team familiarity with patterns