overriding-the-bcl-binding.md

Overriding the BCL binding

At any time, the default binding to the BCL type can be changed to your own:

using Shouldly;
using Pure.DI;

DI.Setup(nameof(Composition))
    .Bind<IDependency[]>().To<IDependency[]>(_ =>
        [new AbcDependency(), new XyzDependency(), new AbcDependency()]
    )
    .Bind<IService>().To<Service>()

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

var composition = new Composition();
var service = composition.Root;
service.Dependencies.Length.ShouldBe(3);
service.Dependencies[0].ShouldBeOfType<AbcDependency>();
service.Dependencies[1].ShouldBeOfType<XyzDependency>();
service.Dependencies[2].ShouldBeOfType<AbcDependency>();

interface IDependency;

class AbcDependency : IDependency;

class XyzDependency : IDependency;

interface IService
{
    IDependency[] Dependencies { get; }
}

class Service(IDependency[] dependencies) : IService
{
    public IDependency[] Dependencies { get; } = dependencies;
}

Running this code sample locally

• Make sure you have the .NET SDK 9.0 or later is installed

dotnet --list-sdk

• Create a net9.0 (or later) console application

dotnet new console -n Sample

• Add references to 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

The following partial class will be generated:

partial class Composition
{
  private readonly Composition _root;

  [OrdinalAttribute(256)]
  public Composition()
  {
    _root = this;
  }

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

  public IService Root
  {
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    get
    {
      IDependency[] transient1 = [new AbcDependency(), new XyzDependency(), new AbcDependency()];
      return new Service(transient1);
    }
  }
}

Class diagram:

---
 config:
  class:
   hideEmptyMembersBox: true
---
classDiagram
	Service --|> IService
	Composition ..> Service : IService Root
	Service *--  ArrayᐸIDependencyᐳ : ArrayᐸIDependencyᐳ
	class ArrayᐸIDependencyᐳ {
			<<array>>
	}
	namespace Pure.DI.UsageTests.BCL.OverridingBclBindingScenario {
		class Composition {
		<<partial>>
		+IService Root
		}
		class IService {
			<<interface>>
		}
		class Service {
			+Service(ArrayᐸIDependencyᐳ dependencies)
		}
	}

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