Advanced Design Patterns

Overview

Transform high-level gameplay requirements into modular, testable, and maintainable systems. This skill enforces strict structural patterns (Strategy, Factory, Observer, Command) adapted for Unity's unique lifecycle.

When to Use

• •Use when implementing any of the GoF design patterns
• •Use when refactoring "God Classes" or circular dependencies
• •Use when creating interchangeable behaviors (Strategy)
• •Use when spawning objects with pooling (Factory)
• •Use when implementing decoupled event systems (Observer)
• •Use when building undo/redo or input replay systems (Command)

Available Patterns

Thinking Process (Mandatory)

Before generating code, analyze:

1. •Identify the Axis of Change: What varies? (Behavior, Creation, Notification)
2. •Pattern Selection: Justify choice based on problem domain
3. •Unity Compatibility: MonoBehaviour vs ScriptableObject vs plain C#
4. •SOLID Validation: SRP and OCP compliance check

Procedure

1. •Generate Architecture Plan: Emit class diagram before implementation
2. •Define Contracts: Create interfaces with clear API boundaries
3. •Implement Concretes: Build decoupled implementations
4. •Inject Dependencies: Use VContainer or SO-based injection (no static Singletons!)
5. •Audit: Verify against constraints

Best Practices

• •✅ Use interfaces as reference types, not concrete classes
• •✅ Prefer composition over inheritance
• •✅ Every Factory for high-frequency objects MUST use Object Pooling
• •✅ Unsubscribe from events in OnDisable/OnDestroy
• •✅ Use [SerializeField] private with _camelCase naming
• •❌ NEVER use GameObject.Find, SendMessage, BroadcastMessage
• •❌ NEVER use large switch/if-else for behavior selection
• •❌ NEVER cast interface back to concrete class

Architecture Audit Checklist

• • SRP Compliance: Each class has single responsibility
• • Memory Safety: Events unsubscribed in OnDestroy
• • Performance: No heap allocations in Update loops

Few-Shot Examples

Example 1: Strategy Pattern for AI

User: "I need different enemy AI behaviors like patrolling, chasing, and retreating."

Agent Output:

1. Generate Implementation Plan with Strategy Pattern
2. Create IEntityBehavior interface
3. Implement PatrolBehavior, ChaseBehavior, RetreatBehavior
4. Create EnemyController with SetBehavior(IBehavior) method
5. Inject behaviors via ScriptableObject references

Example 2: Factory with Pooling

User: "Create a projectile spawning system that doesn't cause GC spikes."

Agent Output:

1. Create IProjectileFactory interface
2. Implement ProjectilePooledFactory : PooledFactory<Projectile>
3. Configure initial pool size based on expected max concurrent
4. Add Return() method call on projectile destruction

Example 3: Observer for UI Updates

User: "Update the health bar when player takes damage without coupling."

Agent Output:

1. Create IHealthObserver interface
2. Create PlayerHealth : ISubject<HealthData>
3. Create HealthBarUI : IObserver<HealthData>
4. Subscribe in OnEnable, unsubscribe in OnDisable

Related Skills

• •@event-bus-system - For global decoupled events
• •@di-container-manager - For dependency injection setup
• •@scriptableobject-architecture - For data-driven pattern implementations

Generator Script

python scripts/pattern_gen.py --pattern strategy --name EnemyAI --namespace Game.AI
python scripts/pattern_gen.py --pattern factory --name Projectile --namespace Game.Combat