# Unity Composition Pattern

> Implements "Composition over Inheritance" using ScriptableObject configs and C# Tuples. Replaces deep class hierarchies with modular, has-a relationships.

- Skill: `muharremtozan/unity-composition-pattern` (Agent Skill, multi-file: 5 files)
- Install (CLI): `npx skillmds@latest add muharremtozan/unity-composition-pattern`
- Raw SKILL.md: https://api.skillmd.com/api/skills/muharremtozan/unity-composition-pattern/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: muharremtozan (https://skillmd.com/u/muharremtozan)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/muharremtozan/unity-composition-pattern

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# Unity Composition Pattern

A fundamental design skill to prevent "Inheritance Hell." This pattern replaces 10 specific classes (e.g., RedStone, GoldStone) with one generic class that composes behaviors from ScriptableObject assets.

## Core Features
1. **Has-A Logic**: Objects define their properties through members (Configs) rather than their base class type.
2. **SO-to-Runtime Bridge**: Uses ScriptableObjects as static data templates that generate dynamic runtime instances.
3. **Tuple Deconstruction**: Uses C# ValueTuples to return multi-part data from composite objects without extra boilerplate.
4. **Hierarchy Flattening**: Drastically reduces the number of C# files needed by offloading variations to Project Assets.

## Core Files (Max 3)
- `EntityConfigSO.cs.txt`: Base class for creating interchangeable data packets.
- `ModularEntity.cs.txt`: The generic container that holds one or more configurations.
- `CompositionExample.cs.txt`: Demonstrates resource harvesting with Tuple destructuring.

## Usage

### 1. Identify "Is-A" vs "Has-A"
- Bad: `ElectricCar : Car : Vehicle` (Inheritance)
- Good: `Vehicle` has an `EngineConfig` (Composition)

### 2. Multi-Value Returns (Tuples)
Instead of internal state-tracking:
```csharp
public (int gold, int weight) Gather() => (10, 5);
// Client destructures instantly:
var (g, w) = node.Gather();
```

### 3. Strategy via SO
Attach different `EntityConfigSO` assets to the same `ModularEntity` to change its identity in the Inspector.