✨ Angular Design Patterns Repository ✨

This repository is a comprehensive guide to design patterns in Angular applications. It covers three main categories of design patterns: Creational, Structural, and Behavioral. Each section includes multiple examples and guidance on how to identify these patterns in Angular source code.

Table of Contents

1. Creational Patterns
2. Structural Patterns
3. Behavioral Patterns
4. How to Use This Repository

Creational Patterns

Creational patterns provide various object creation mechanisms, which increase flexibility and reuse of existing code.

Patterns covered:

• Factory Method
• Abstract Factory
• Builder
• Prototype
• Singleton

Examples:

1. Singleton Pattern

   • Use case: Shared service instances across the application
   • Example: Angular's built-in services like HttpClient
   • How to find: Look for @Injectable({ providedIn: 'root' }) decorators

2. Factory Method Pattern

   • Use case: Creating objects without specifying the exact class of object to be created
   • Example: Using a service to create different types of form controls
   • How to find: Look for methods that return instances of a common interface or base class

3. Builder Pattern

   • Use case: Complex object construction
   • Example: Using FormBuilder to create complex reactive forms
   • How to find: Look for FormBuilder injection and usage in component files

Structural Patterns

Structural patterns explain how to assemble objects and classes into larger structures while keeping these structures flexible and efficient.

Patterns covered:

• Adapter
• Bridge
• Composite
• Decorator
• Facade
• Flyweight
• Proxy

Examples:

1. Decorator Pattern

   • Use case: Adding behavior to components or services without modifying their code
   • Example: Using Angular decorators like @Component, @Injectable, or custom property decorators
   • How to find: Look for @ symbols followed by decorator names in class definitions

2. Proxy Pattern

   • Use case: Lazy loading of modules or components
   • Example: Using Angular's router for lazy loading feature modules
   • How to find: Check RouterModule configurations in app routing files for lazy-loaded routes

3. Composite Pattern

   • Use case: Building complex UI structures from simpler components
   • Example: Nested components in Angular templates
   • How to find: Analyze component templates for nested custom elements

Behavioral Patterns

Behavioral patterns are concerned with algorithms and the assignment of responsibilities between objects.

Patterns covered:

• Chain of Responsibility
• Command
• Iterator
• Mediator
• Memento
• Observer
• State
• Strategy
• Template Method
• Visitor

Examples:

1. Observer Pattern

   • Use case: Reactive programming with RxJS
   • Example: Using Subject or BehaviorSubject for state management
   • How to find: Look for RxJS import statements and usage of Observables in services and components

2. Strategy Pattern

   • Use case: Implementing different algorithms or strategies that can be switched at runtime
   • Example: Using different validation strategies in reactive forms
   • How to find: Search for classes or functions that implement a common interface but with different logic

3. Command Pattern

   • Use case: Encapsulating a request as an object
   • Example: Implementing undo/redo functionality or action creators in NgRx
   • How to find: Look for classes that encapsulate all information needed to perform an action or trigger an event

How to Use This Repository

1. Browse through the different pattern categories to understand their use cases in Angular applications.
2. Each pattern includes practical examples and tips on how to identify them in existing codebases.
3. Use the provided examples as inspiration for implementing these patterns in your own Angular projects.
4. Contribute your own examples or improvements by submitting pull requests.

Remember, while design patterns can greatly improve your code structure and maintainability, they should be used judiciously. Always consider the specific needs of your project when deciding to implement a particular pattern.

Happy coding!