root-type.md

Root Type

RootType provides the type of the composition root being resolved. This property is useful for implementing root-specific behavior like different caching strategies per root type. Use this when infrastructure dependencies must vary by root contract type.

using Shouldly;
using Pure.DI;

var composition = new Composition();
var orderService = composition.OrderService;
orderService.Cache.Set("order_123", "Order Data");
orderService.Cache.Get("order_123").ShouldBe("Order Data");
orderService.Cache.KeyPrefix.ShouldBe("IOrderService");

var inventoryService = composition.InventoryService;
inventoryService.Cache.Set("item_456", "Item Data");
inventoryService.Cache.Get("item_456").ShouldBe("Item Data");
inventoryService.Cache.KeyPrefix.ShouldBe("IInventoryService");

interface ICache
{
    string KeyPrefix { get; }

    void Set(string key, string value);

    string Get(string key);
}

interface IOrderService
{
    ICache Cache { get; }
}

interface IInventoryService
{
    ICache Cache { get; }
}

class Cache(Type rootType) : ICache
{
    private readonly Dictionary<string, string> _data = new();

    public string KeyPrefix => rootType.Name;

    public void Set(string key, string value) => _data[key] = value;

    public string Get(string key) => _data.TryGetValue(key, out var value) ? value : string.Empty;
}

class OrderService(ICache cache) : IOrderService
{
    public ICache Cache => cache;
}

class InventoryService(ICache cache) : IInventoryService
{
    public ICache Cache => cache;
}

partial class Composition
{
    private void Setup() =>

        DI.Setup(nameof(Composition))
            .Bind().To(ctx => new Cache(ctx.RootType))
            .Bind().To<OrderService>()
            .Root<IOrderService>("OrderService")
            .Bind().To<InventoryService>()
            .Root<IInventoryService>("InventoryService");
}

Running this code sample locally

• Make sure you have the .NET SDK 10.0 or later installed

dotnet --list-sdk

• Create a net10.0 (or later) console application

dotnet new console -n Sample

• Add references to the NuGet packages
  • Pure.DI
  • Shouldly

dotnet add package Pure.DI
dotnet add package Shouldly

• Copy the example code into the Program.cs file

You are ready to run the example 🚀

dotnet run

Limitations: root-type-specific rules can become hidden policy; keep this logic centralized and observable. See also: Composition roots, Root Name.

The following partial class will be generated:

partial class Composition
{
  public IOrderService OrderService
  {
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    get
    {
      Cache transientCache101 = new Cache(typeof(IOrderService));
      return new OrderService(transientCache101);
    }
  }

  public IInventoryService InventoryService
  {
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    get
    {
      Cache transientCache99 = new Cache(typeof(IInventoryService));
      return new InventoryService(transientCache99);
    }
  }
}

Class diagram:

---
 config:
  maxTextSize: 2147483647
  maxEdges: 2147483647
  class:
   hideEmptyMembersBox: true
---
classDiagram
	Cache --|> ICache
	OrderService --|> IOrderService
	InventoryService --|> IInventoryService
	Composition ..> InventoryService : IInventoryService InventoryService
	Composition ..> OrderService : IOrderService OrderService
	OrderService *--  Cache : ICache
	InventoryService *--  Cache : ICache
	namespace Pure.DI.UsageTests.Advanced.RootTypeScenario {
		class Cache {
				<<class>>
		}
		class Composition {
		<<partial>>
		+IInventoryService InventoryService
		+IOrderService OrderService
		}
		class ICache {
			<<interface>>
		}
		class IInventoryService {
			<<interface>>
		}
		class InventoryService {
				<<class>>
			+InventoryService(ICache cache)
		}
		class IOrderService {
			<<interface>>
		}
		class OrderService {
				<<class>>
			+OrderService(ICache cache)
		}
	}

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