This repository contains implementations of various famous Design Patterns in C#/.NET, inspired by the examples and concepts from the book:
Head First Design Patterns
The goal of this repository is to deeply understand:
- Object-Oriented Design Principles
- Reusable Software Architecture
- Decoupled System Design
- Maintainable and Scalable Code
Each pattern is implemented with practical examples to demonstrate:
- The problem the pattern solves
- How the pattern works internally
- Real-world use cases
Design Patterns are reusable solutions to common software design problems.
They are not ready-made code, but proven architectural approaches that help developers build:
- Flexible systems
- Maintainable code
- Loosely coupled applications
- Scalable software architectures
Design Patterns are widely used in:
- Frameworks
- Enterprise applications
- Game engines
- Distributed systems
- UI frameworks
- Cloud applications
Converts one interface into another interface that a client expects.
A mobile charger adapter converts high-voltage wall power into a format your phone can use.
- Object Adapter
- Interface conversion
- Legacy system integration
Encapsulates a request as an object.
A restaurant waiter takes your order and sends it to the kitchen without needing to know how the food is prepared.
- Command objects
- Undo operations
- Decoupling sender and receiver
Treats individual objects and groups of objects uniformly.
A file system where files and folders are treated similarly.
- Tree structures
- Recursive composition
- Uniform object handling
Adds new behavior to objects dynamically without modifying existing code.
Adding toppings to a pizza or coffee without changing the original item.
- Runtime behavior extension
- Composition over inheritance
- Flexible feature additions
Defines an interface for object creation while letting subclasses decide which object to create.
A logistics company creating different transport objects like Truck, Ship, or Air Cargo depending on delivery type.
- Object creation abstraction
- Loose coupling
- Polymorphic instantiation
Defines a one-to-many dependency between objects so that when one object changes state, all dependents are notified automatically.
YouTube subscribers receiving notifications when a creator uploads a new video.
- Event-driven architecture
- Publish-subscribe model
- Reactive communication
Provides a way to access elements of a collection sequentially without exposing its internal structure.
Scrolling through songs in a music playlist.
- Sequential traversal
- Collection abstraction
- Encapsulated iteration logic
The Proxy Pattern provides a placeholder or surrogate object to control access to another object.
This repository includes multiple types of proxies.
Represents an object located on a remote server.
A local application communicating with a remote cloud service.
- Remote communication abstraction
- Distributed systems design
- Network transparency
Controls access to expensive objects by creating them only when needed.
Lazy loading high-resolution images on websites.
- Lazy initialization
- Performance optimization
- Resource management
Controls access to an object based on permissions.
Admin panels where only authorized users can modify settings.
- Access control
- Authorization
- Security abstraction
Ensures that only one instance of a class exists.
Application-wide configuration manager or logging service.
- Controlled instantiation
- Global shared state
- Thread-safe singleton concepts
Allows an object to alter its behavior when its internal state changes.
A vending machine behaving differently depending on whether it has money inserted or not.
- State-driven behavior
- Eliminating large conditionals
- Dynamic behavior switching
Defines the skeleton of an algorithm while allowing subclasses to customize specific steps.
Making beverages where boiling water is common, but tea and coffee preparation differ.
- Algorithm standardization
- Hook methods
- Code reuse through inheritance
Each design pattern folder contains a dedicated *TestDrive.cs file used to test and experiment with that specific pattern implementation.
Example:
namespace DesignPatterns.IteratorPattern
{
public class IteratorPatternTestDrive : TestDrive
{
public static void test()
{
/* Write the code here to test the implementation of the Iterator Pattern */
Console.WriteLine("Iterator Pattern Test Drive");
}
}
}These test drive classes act as small entry points for:
- Testing pattern behavior
- Understanding object interactions
- Experimenting with different implementations
- Learning how the pattern works internally
To test a pattern:
- Open the corresponding
*TestDrive.csfile - Write or modify the test code
- Call the
test()method fromProgram.cs
Example:
IteratorPatternTestDrive.test();This structure keeps:
- Pattern implementation separated
- Testing clean and modular
- Code easy to navigate and extend
- C#
- .NET
- Object-Oriented Programming
- SOLID Principles
This repository was created to:
- Practice software design principles
- Understand low-level architecture
- Improve object-oriented thinking
- Learn enterprise-level coding practices
- Explore reusable software patterns
Potential future additions:
- Strategy Pattern
- Facade Pattern
- Builder Pattern
- Flyweight Pattern
- Mediator Pattern
- Dependency Injection examples
- Multithreaded pattern implementations
- Head First Design Patterns
- Gang of Four (GoF) Design Patterns
- Microsoft .NET Documentation
Saurabh Garg
Passionate about:
- Software Engineering
- System Design
- Backend Development
- Architecture Patterns
- Scalable Applications