roots-with-filter.md

Roots with filter

Demonstrates how to create roots for types that match specific filter criteria, allowing selective exposure of implementations.

using Shouldly;
using Pure.DI;

DI.Setup(nameof(Composition))
    .Bind().As(Lifetime.Singleton).To<Configuration>()
    .Roots<INotificationService>("My{type}", filter: "*Email*");

var composition = new Composition();
composition.MyEmailService.ShouldBeOfType<EmailService>();

interface IConfiguration;

class Configuration : IConfiguration;

interface INotificationService;

// This service requires an API key which is not bound,
// so it cannot be resolved and should be filtered out.
class SmsService(string apiKey) : INotificationService;

class EmailService(IConfiguration config) : INotificationService;

Running this code sample locally

• Make sure you have the .NET SDK 10.0 or later installed

dotnet --list-sdk

• Create a net10.0 (or later) console application

dotnet new console -n Sample

• Add references to the 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

Note

Filtering roots provides fine-grained control over which implementations are exposed, useful for conditional feature activation.

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 Configuration? _singletonConfiguration62;

  public EmailService MyEmailService
  {
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    get
    {
      if (_singletonConfiguration62 is null)
        lock (_lock)
          if (_singletonConfiguration62 is null)
          {
            _singletonConfiguration62 = new Configuration();
          }

      return new EmailService(_singletonConfiguration62);
    }
  }
}

Class diagram:

---
 config:
  maxTextSize: 2147483647
  maxEdges: 2147483647
  class:
   hideEmptyMembersBox: true
---
classDiagram
	Configuration --|> IConfiguration
	Composition ..> EmailService : EmailService MyEmailService
	EmailService o-- "Singleton" Configuration : IConfiguration
	namespace Pure.DI.UsageTests.Basics.RootsWithFilterScenario {
		class Composition {
		<<partial>>
		+EmailService MyEmailService
		}
		class Configuration {
				<<class>>
			+Configuration()
		}
		class EmailService {
				<<class>>
			+EmailService(IConfiguration config)
		}
		class IConfiguration {
			<<interface>>
		}
	}

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