Code Reviewing Advanced Patterns

In this lesson, you will learn how to provide constructive feedback on complex class hierarchies and design pattern implementations during peer reviews.

When reviewing code that uses advanced patterns, it is easy to get lost in the syntax. Instead of focusing on how the code is written, focus on why a pattern was chosen and whether it aligns with the system's architecture.

Look for "Pattern Overkill"

Advanced patterns like Strategy, Decorator, or State machines are powerful, but they increase architectural complexity. During a code review, ask yourself: "Is this abstraction truly solving a problem, or is it adding unnecessary indirection?"

For example, if you see a simple if statement replaced by a complex Strategy pattern hierarchy, provide feedback like this:

"I see we’ve introduced an IPriceStrategy interface here. Since we only have two pricing types and no plans to add more, would a simple switch expression suffice? This would reduce our class count and make the logic easier to trace."

Validate Inheritance Integrity

When reviewing class hierarchies, ensure that the "is-a" relationship is strictly maintained. Developers often use inheritance just to share code, which leads to "fragile base class" issues. If a class overrides a method to throw a NotImplementedException, the hierarchy is likely broken.

Suggest a shift toward composition:

// Instead of inheriting from a bloated BaseManager:
public class Service : IService {
    private readonly ILogger _logger;
    // Injecting behavior instead of inheriting it
}

Provide Actionable Architectural Feedback

Your goal as a reviewer is to protect the system's design. When you encounter a pattern that doesn't fit, suggest an alternative based on the concepts you’ve mastered, such as moving logic into a domain event or simplifying a middleware pipeline. Frame your comments as questions rather than demands. Use phrases like, "How does this fit into our bounded context boundaries?" or "Would a more immutable approach reduce the side effects we see here?"

By focusing on architectural intent rather than just syntax, you help your peers evolve the codebase without falling into the trap of "pattern addiction."

Key Takeaway: Effective code reviews for advanced patterns should prioritize architectural simplicity and clear intent over the clever application of design patterns.