unity-pattern-service-locator

name	unity-pattern-service-locator
description	Service Locator
category	unity
source	unity-design-patterns-skills
source_path	patterns/service-locator/SKILL.md

Service Locator

Purpose

Resolve shared services through a central registry as a constrained bridge when explicit injection is not yet practical everywhere.

Use When

• Legacy or callback-heavy code makes immediate DI hard.
• A temporary migration bridge is needed.
• Bootstrap can control registration order.

Avoid When

• You are designing a new architecture from scratch.
• Hidden dependencies would materially hurt the feature.

Unity Implementation Recipe

1. Constrain the allowed services.
2. Register at bootstrap.
3. Document lookup points.
4. Provide test reset or override hooks.

Common Pitfalls

• A global grab-bag of unrelated services.
• Initialization order bugs.

Minimal Unity Sketch

public static class Services
{
    private static readonly Dictionary<Type, object> _map = new();
    public static void Register<T>(T service) where T : class => _map[typeof(T)] = service;
    public static T Get<T>() where T : class => (T)_map[typeof(T)];
}

Response Shape

• Say whether Service Locator is actually the right fit.
• Map it to concrete Unity types, ownership, and lifecycle.
• Prefer a production-shaped skeleton over a long tutorial dump.
• Call out the simpler alternative if this pattern would be overengineering.