roots.md

July 5, 2026 · View on GitHub

Roots

Sometimes you need roots for all types inherited from available at compile time at the point where the method is called.

using Shouldly;
using Pure.DI;

DI.Setup(nameof(Composition))
    .Bind().As(Lifetime.Singleton).To<Preferences>()
    // Roots can be used to register all descendants of a type as roots.
    .Roots<IWindow>("{type}");

var composition = new Composition();
composition.MainWindow.ShouldBeOfType<MainWindow>();
composition.SettingsWindow.ShouldBeOfType<SettingsWindow>();

interface IPreferences;

class Preferences : IPreferences;

interface IWindow;

class MainWindow(IPreferences preferences) : IWindow;

class SettingsWindow(IPreferences preferences) : IWindow;
Running this code sample locally 
dotnet --list-sdk
  • Create a net10.0 (or later) console application
dotnet new console -n Sample

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

Note

This feature is useful for plugin-style architectures where you need to expose all implementations of a base type or interface.

The following partial class will be generated 
partial class Composition
{
#if NET9_0_OR_GREATER
  private readonly Lock _lock = new Lock();
#else
  private readonly Object _lock = new Object();
#endif

  private Preferences? _singletonCompositionInOtherProject;

  public SettingsWindow SettingsWindow
  {
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    get
    {
      if (_singletonCompositionInOtherProject is null)
        lock (_lock)
          if (_singletonCompositionInOtherProject is null)
          {
            _singletonCompositionInOtherProject = new Preferences();
          }

      return new SettingsWindow(_singletonCompositionInOtherProject);
    }
  }

  public MainWindow MainWindow
  {
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    get
    {
      if (_singletonCompositionInOtherProject is null)
        lock (_lock)
          if (_singletonCompositionInOtherProject is null)
          {
            _singletonCompositionInOtherProject = new Preferences();
          }

      return new MainWindow(_singletonCompositionInOtherProject);
    }
  }
}

Class diagram:

---
 config:
  class:
   hideEmptyMembersBox: true
---
classDiagram
	Preferences --|> IPreferences
	Composition ..> SettingsWindow : SettingsWindow SettingsWindow
	Composition ..> MainWindow : MainWindow MainWindow
	SettingsWindow o-- "Singleton" Preferences : IPreferences
	MainWindow o-- "Singleton" Preferences : IPreferences
	namespace Pure.DI.UsageTests.Basics.RootsScenario {
		class Composition {
		<<partial>>
		+MainWindow MainWindow
		+SettingsWindow SettingsWindow
		}
		class IPreferences {
			<<interface>>
		}
		class MainWindow {
				<<class>>
			+MainWindow(IPreferences preferences)
		}
		class Preferences {
				<<class>>
			+Preferences()
		}
		class SettingsWindow {
				<<class>>
			+SettingsWindow(IPreferences preferences)
		}
	}

See also: