System Design & Design Patterns

Key Takeaways

Design patterns best practices and common pitfalls

Design Patterns Best Practices

Problem-Driven

Identify real problems first, Don't force patterns, Consider alternatives

Combination

Patterns work together, Real systems use multiple patterns, Understand interactions

Trade-offs

Complexity vs benefits, Performance implications, Maintainability focus

Evolution

Start simple, Refactor when needed, Don't over-engineer upfront

Patterns work together, not in isolation
Real systems use multiple patterns at once
Understand how patterns interact, recall the e-commerce case study
Factory, Builder, Strategy, Observer, Decorator, Command, and Facade all cooperated in one flow

Choose patterns based on problems, not preferences: each pattern solves specific design problems
Don't over-engineer: use patterns when they genuinely improve code quality
Patterns work together: real systems often combine multiple patterns
Focus on maintainability: patterns should make code easier to understand and modify
Consider trade-offs: patterns add complexity but solve bigger problems

Anti-Patterns

Pattern Obsession

God Object Facade

Singleton Abuse

Strategy Explosion

Observer Chaos

Mahmoud AbasKey Takeaways