generic-composition-roots-with-constraints.md

Generic composition roots with constraints

Important

`Resolve' methods cannot be used to resolve generic composition roots.

interface IDependency<T>
    where T : IDisposable;

class Dependency<T> : IDependency<T>
    where T : IDisposable;

interface IService<T, TStruct>
    where T : IDisposable
    where TStruct : struct;

class Service<T, TStruct>(IDependency<T> dependency) : IService<T, TStruct>
    where T : IDisposable
    where TStruct : struct;

class OtherService<T>(IDependency<T> dependency) : IService<T, bool>
    where T : IDisposable;

DI.Setup(nameof(Composition))
    // This hint indicates to not generate methods such as Resolve
    .Hint(Hint.Resolve, "Off")
    .Bind().To<Dependency<TTDisposable>>()
    .Bind().To<Service<TTDisposable, TTS>>()
    // Creates OtherService manually,
    // just for the sake of example
    .Bind("Other").To(ctx =>
    {
        ctx.Inject(out IDependency<TTDisposable> dependency);
        return new OtherService<TTDisposable>(dependency);
    })

    // Specifies to create a regular public method
    // to get a composition root of type Service<T, TStruct>
    // with the name "GetMyRoot"
    .Root<IService<TTDisposable, TTS>>("GetMyRoot")

    // Specifies to create a regular public method
    // to get a composition root of type OtherService<T>
    // with the name "GetOtherService"
    // using the "Other" tag
    .Root<IService<TTDisposable, bool>>("GetOtherService", "Other");

var composition = new Composition();

// service = new Service<Stream, double>(new Dependency<Stream>());
var service = composition.GetMyRoot<Stream, double>();

// someOtherService = new OtherService<BinaryReader>(new Dependency<BinaryReader>());
var someOtherService = composition.GetOtherService<BinaryReader>();

Important

The method Inject()cannot be used outside of the binding setup.

The following partial class will be generated:

partial class Composition
{
  private readonly Composition _root;

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

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

  [MethodImpl(MethodImplOptions.AggressiveInlining)]
  public IService<T, bool> GetOtherService<T>()
    where T: IDisposable
  {
    OtherService<T> transientOtherService0;
    IDependency<T> localDependency61 = new Dependency<T>();
    transientOtherService0 = new OtherService<T>(localDependency61);
    return transientOtherService0;
  }

  [MethodImpl(MethodImplOptions.AggressiveInlining)]
  public IService<T, T1> GetMyRoot<T, T1>()
    where T: IDisposable
    where T1: struct
  {
    return new Service<T, T1>(new Dependency<T>());
  }
}

Class diagram:

classDiagram
	class Composition {
		<<partial>>
		+IServiceᐸTˏT1ᐳ GetMyRootᐸTˏT1ᐳ()
		+IServiceᐸTˏBooleanᐳ GetOtherServiceᐸTᐳ()
	}
	OtherServiceᐸTᐳ --|> IServiceᐸTˏBooleanᐳ : "Other" 
	class OtherServiceᐸTᐳ
	ServiceᐸTˏT1ᐳ --|> IServiceᐸTˏT1ᐳ
	class ServiceᐸTˏT1ᐳ {
		+Service(IDependencyᐸTᐳ dependency)
	}
	DependencyᐸTᐳ --|> IDependencyᐸTᐳ
	class DependencyᐸTᐳ {
		+Dependency()
	}
	class IServiceᐸTˏBooleanᐳ {
		<<interface>>
	}
	class IServiceᐸTˏT1ᐳ {
		<<interface>>
	}
	class IDependencyᐸTᐳ {
		<<interface>>
	}
	Composition ..> OtherServiceᐸTᐳ : IServiceᐸTˏBooleanᐳ GetOtherServiceᐸTᐳ()
	Composition ..> ServiceᐸTˏT1ᐳ : IServiceᐸTˏT1ᐳ GetMyRootᐸTˏT1ᐳ()
	OtherServiceᐸTᐳ *--  DependencyᐸTᐳ : IDependencyᐸTᐳ
	ServiceᐸTˏT1ᐳ *--  DependencyᐸTᐳ : IDependencyᐸTᐳ

Loading