Design Patterns Mastery
1. Introduction to Design Patterns
Introduction to GoF Patterns: Why patterns matter? SOLID Principles: The foundation of all patterns DRY, KISS, and YAGNI (Architectural Philosophy)
2. Creational Patterns
Singleton Pattern: Thread-safety & Captive Dependencies Factory Method: Abstracting complex object creation Abstract Factory: Creating families of related objects Builder Pattern: Constructing complex fluents Prototype Pattern: Cloning high-cost objects
3. Structural Patterns
Adapter Pattern: Bridging incompatible interfaces Bridge Pattern: Decoupling abstraction from implementation Composite Pattern: Managing tree structures & hierarchies Decorator Pattern: Enhancing behavior without inheritance Facade Pattern: Simplifying complex library subsystems Flyweight Pattern: Drastically reducing memory footprint Proxy Pattern: Interception, Lazy-Loading, and Security
4. Behavioral Patterns
Chain of Responsibility: Middleware & Pipeline Architecture Command Pattern: Implementing Undo/Redo & Queueing Interpreter Pattern: Building domain-specific languages Iterator Pattern: Unified traversal of collections Mediator Pattern: Decoupling components with MediatR Memento Pattern: Capturing and restoring object state Observer Pattern: Pub/Sub & Event-driven architecture State Pattern: Managing complex object lifecycles Strategy Pattern: Swappable algorithms at runtime Template Method: Defining skeleton algorithms Visitor Pattern: Separating operations from data structures
5. Modern Enterprise & Cloud Patterns
Repository & Unit of Work (The EF Core Standard) CQRS Pattern (Command Query Responsibility Segregation) Circuit Breaker & Retry Patterns (Resilience with Polly) Dependency Injection Pattern (The Modern King)
Design Patterns Mastery

DRY, KISS, and YAGNI (Architectural Philosophy)

1 Views Updated 5/4/2026

DRY, KISS, and YAGNI

Beyond patterns and principles lie the "Common Sense" rules of architecture. These acronyms act as a filter during code reviews to ensure your system doesn't collapse under its own weight.

1. DRY: Don't Repeat Yourself

Every piece of knowledge or logic must have a single, unambiguous representation within a system. Duplicated code is a bug waiting to happen. However, beware of "Atheistic DRY"—where you DRY out code that just happens to look similar but represents different business concepts.

2. KISS: Keep It Simple, Stupid

The most elegant solution is the simplest one. Complexity is a cost that must be justified. If you can solve a problem with a simple switch expression, don't build a complex State Pattern with 10 classes.

3. YAGNI: You Ain't Gonna Need It

Software developers are addicted to speculating about the future. "What if the client wants to switch to Oracle next month?" So they spend 3 weeks building a generic database abstraction. YAGNI tells you: Only build what you need for the current requirement. Future-proofing is often just wasted effort and added maintenance.

4. Interview Mastery

Q: "When is it okay to violate DRY (Don't Repeat Yourself)?"

Architect Answer: "DRY should be violated when centralizing the logic would create a **Tight Coupling** between two unrelated business domains. For example, a 'User' in the Identity service and a 'User' in the Billing service might look exactly the same today, but they will evolve differently tomorrow. If you merge them into a single shared class just to satisfy DRY, you've created a dependency that will make it impossible to change Billing without breaking login logic. In this case, 'Clean Duplication' is better than a 'Dirty Abstraction'."

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Design Patterns Mastery
1. Introduction to Design Patterns
Introduction to GoF Patterns: Why patterns matter? SOLID Principles: The foundation of all patterns DRY, KISS, and YAGNI (Architectural Philosophy)
2. Creational Patterns
Singleton Pattern: Thread-safety & Captive Dependencies Factory Method: Abstracting complex object creation Abstract Factory: Creating families of related objects Builder Pattern: Constructing complex fluents Prototype Pattern: Cloning high-cost objects
3. Structural Patterns
Adapter Pattern: Bridging incompatible interfaces Bridge Pattern: Decoupling abstraction from implementation Composite Pattern: Managing tree structures & hierarchies Decorator Pattern: Enhancing behavior without inheritance Facade Pattern: Simplifying complex library subsystems Flyweight Pattern: Drastically reducing memory footprint Proxy Pattern: Interception, Lazy-Loading, and Security
4. Behavioral Patterns
Chain of Responsibility: Middleware & Pipeline Architecture Command Pattern: Implementing Undo/Redo & Queueing Interpreter Pattern: Building domain-specific languages Iterator Pattern: Unified traversal of collections Mediator Pattern: Decoupling components with MediatR Memento Pattern: Capturing and restoring object state Observer Pattern: Pub/Sub & Event-driven architecture State Pattern: Managing complex object lifecycles Strategy Pattern: Swappable algorithms at runtime Template Method: Defining skeleton algorithms Visitor Pattern: Separating operations from data structures
5. Modern Enterprise & Cloud Patterns
Repository & Unit of Work (The EF Core Standard) CQRS Pattern (Command Query Responsibility Segregation) Circuit Breaker & Retry Patterns (Resilience with Polly) Dependency Injection Pattern (The Modern King)