bind-attribute-with-lifetime-and-tag.md

Bind attribute with lifetime and tag

interface IDependency
{
    public void DoSomething();
}

class Dependency : IDependency
{
    public void DoSomething()
    {
    }
}

class Facade
{
    [Bind(lifetime: Lifetime.Singleton, tags: ["my tag"])]
    public IDependency Dependency { get; } = new Dependency();
}

interface IService
{
    public void DoSomething();
}

class Service([Tag("my tag")] IDependency dep) : IService
{
    public void DoSomething() => dep.DoSomething();
}

DI.Setup(nameof(Composition))
    .Bind().As(Lifetime.Singleton).To<Facade>()
    .Bind().To<Service>()

    // Composition root
    .Root<IService>("Root");

var composition = new Composition();
var service = composition.Root;
service.DoSomething();

The following partial class will be generated:

partial class Composition
{
  private readonly Composition _root;
  private readonly object _lock;

  private IDependency? _singletonIDependency0;
  private Facade? _singletonFacade39;

  [OrdinalAttribute(20)]
  public Composition()
  {
    _root = this;
    _lock = new object();
  }

  internal Composition(Composition parentScope)
  {
    _root = (parentScope ?? throw new ArgumentNullException(nameof(parentScope)))._root;
    _lock = _root._lock;
  }

  public IService Root
  {
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    get
    {
      if (_root._singletonIDependency0 == null)
      {
        lock (_lock)
        {
          if (_root._singletonIDependency0 == null)
          {
            if (_root._singletonFacade39 == null)
            {
              _root._singletonFacade39 = new Facade();
            }

            Facade localInstance_1182D12732 = _root._singletonFacade39!;
            _root._singletonIDependency0 = localInstance_1182D12732.Dependency;
          }
        }
      }

      return new Service(_root._singletonIDependency0!);
    }
  }
}

Class diagram:

classDiagram
	class Composition {
		<<partial>>
		+IService Root
	}
	class IDependency
	class Facade {
		+Facade()
	}
	Service --|> IService
	class Service {
		+Service(IDependency dep)
	}
	class IService {
		<<interface>>
	}
	Composition ..> Service : IService Root
	IDependency o-- "Singleton" Facade : Facade
	Service o-- "Singleton" IDependency : "my tag"  IDependency

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