exposed-generic-roots-with-args.md

Exposed generic roots with args

Composition roots from other assemblies or projects can be used as a source of bindings. When you add a binding to a composition from another assembly or project, the roots of the composition with the RootKind.Exposed type will be used in the bindings automatically. For example, in some assembly a composition is defined as:

public partial class CompositionWithGenericRootsAndArgsInOtherProject
{
    private static void Setup() =>
        DI.Setup()
            .Hint(Hint.Resolve, "Off")
            .RootArg<int>("id")
            .Bind().As(Lifetime.Singleton).To<MyDependency>()
            .Bind().To<MyGenericService<TT>>()
            .Root<IMyGenericService<TT>>("GetMyService", kind: RootKinds.Exposed);
}

class Program(IMyGenericService<int> myService)
{
    public void DoSomething(int value) => myService.DoSomething(value);
}

DI.Setup(nameof(Composition))
    .Hint(Hint.Resolve, "Off")
    .RootArg<int>("id")
    // Binds to exposed composition roots from other project
    .Bind().As(Lifetime.Singleton).To<CompositionWithGenericRootsAndArgsInOtherProject>()
    .Root<Program>("GetProgram");

var composition = new Composition();
var program = composition.GetProgram(33);
program.DoSomething(99);

The following partial class will be generated:

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

  private Integration.CompositionWithGenericRootsAndArgsInOtherProject? _singletonCompositionWithGenericRootsAndArgsInOtherProject42;

  [OrdinalAttribute(10)]
  public Composition()
  {
    _root = this;
    _lock = new Lock();
  }

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

  [MethodImpl(MethodImplOptions.AggressiveInlining)]
  public Program GetProgram(int id)
  {
    if (_root._singletonCompositionWithGenericRootsAndArgsInOtherProject42 is null)
    {
      using (_lock.EnterScope())
      {
        if (_root._singletonCompositionWithGenericRootsAndArgsInOtherProject42 is null)
        {
          _root._singletonCompositionWithGenericRootsAndArgsInOtherProject42 = new Integration.CompositionWithGenericRootsAndArgsInOtherProject();
        }
      }
    }

    Integration.IMyGenericService<int> transientIMyGenericService1;
    int localId1 = id;
    Integration.CompositionWithGenericRootsAndArgsInOtherProject localInstance_1182D1272 = _root._singletonCompositionWithGenericRootsAndArgsInOtherProject42!;
    transientIMyGenericService1 = localInstance_1182D1272.GetMyService<int>(localId1);
    return new Program(transientIMyGenericService1);
  }
}