builders-with-a-name-template.md

Builders with a name template

Sometimes you need to build up an existing composition root and inject all of its dependencies, in which case the Builder method will be useful, as in the example below:

using Shouldly;
using Pure.DI;

DI.Setup(nameof(Composition))
    .Bind().To(Guid.NewGuid)
    .Bind().To<WiFi>()
    // Creates a builder based on the name template
    // for each type inherited from IDevice.
    // These types must be available at this point in the code.
    .Builders<IDevice>("Install{type}");

var composition = new Composition();

var webcam = composition.InstallWebcam(new Webcam());
webcam.Id.ShouldNotBe(Guid.Empty);
webcam.Network.ShouldBeOfType<WiFi>();

var thermostat = composition.InstallThermostat(new Thermostat());
thermostat.Id.ShouldBe(Guid.Empty);
thermostat.Network.ShouldBeOfType<WiFi>();

// Uses a common method to build an instance
IDevice device = new Webcam();
device = composition.InstallIDevice(device);
device.ShouldBeOfType<Webcam>();
device.Id.ShouldNotBe(Guid.Empty);
device.Network.ShouldBeOfType<WiFi>();

interface INetwork;

class WiFi : INetwork;

interface IDevice
{
    Guid Id { get; }

    INetwork? Network { get; }
}

record Webcam : IDevice
{
    public Guid Id { get; private set; } = Guid.Empty;

    // The Dependency attribute specifies to perform an injection
    [Dependency]
    public INetwork? Network { get; set; }

    [Dependency]
    public void SetId(Guid id) => Id = id;
}

record Thermostat : IDevice
{
    public Guid Id => Guid.Empty;

    // The Dependency attribute specifies to perform an injection
    [Dependency]
    public INetwork? Network { get; set; }
}

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

The default builder method name is BuildUp. The first argument to this method will always be the instance to be built.

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

  [MethodImpl(MethodImplOptions.AggressiveInlining)]
  public Webcam InstallWebcam(Webcam buildingInstance)
  {
    if (buildingInstance is null) throw new ArgumentNullException(nameof(buildingInstance));
    Webcam transientWebcam259;
    Webcam localBuildingInstance6 = buildingInstance;
    Guid transientGuid262 = Guid.NewGuid();
    localBuildingInstance6.Network = new WiFi();
    localBuildingInstance6.SetId(transientGuid262);
    transientWebcam259 = localBuildingInstance6;
    return transientWebcam259;
  }

  [MethodImpl(MethodImplOptions.AggressiveInlining)]
  public Thermostat InstallThermostat(Thermostat buildingInstance)
  {
    if (buildingInstance is null) throw new ArgumentNullException(nameof(buildingInstance));
    Thermostat transientThermostat256;
    Thermostat localBuildingInstance5 = buildingInstance;
    localBuildingInstance5.Network = new WiFi();
    transientThermostat256 = localBuildingInstance5;
    return transientThermostat256;
  }

  #pragma warning disable CS0162
  [MethodImpl(MethodImplOptions.NoInlining)]
  public IDevice InstallIDevice(IDevice buildingInstance)
  {
    if (buildingInstance is null) throw new ArgumentNullException(nameof(buildingInstance));
    switch (buildingInstance)
    {
      case Webcam Webcam:
        return InstallWebcam(Webcam);
      case Thermostat Thermostat:
        return InstallThermostat(Thermostat);
      default:
        throw new ArgumentException($"Unable to build an instance of typeof type {buildingInstance.GetType()}.", "buildingInstance");
    }
    return buildingInstance;
  }
  #pragma warning restore CS0162
}

Class diagram:

---
 config:
  maxTextSize: 2147483647
  maxEdges: 2147483647
  class:
   hideEmptyMembersBox: true
---
classDiagram
	Guid --|> IComparable
	Guid --|> IComparableᐸGuidᐳ
	Guid --|> IEquatableᐸGuidᐳ
	Guid --|> IFormattable
	Guid --|> IParsableᐸGuidᐳ
	Guid --|> ISpanFormattable
	Guid --|> ISpanParsableᐸGuidᐳ
	Guid --|> IUtf8SpanFormattable
	Guid --|> IUtf8SpanParsableᐸGuidᐳ
	WiFi --|> INetwork
	Composition ..> IDevice : IDevice InstallIDevice(Pure.DI.UsageTests.Basics.BuildersWithNameTemplateScenario.IDevice buildingInstance)
	Composition ..> Thermostat : Thermostat InstallThermostat(Pure.DI.UsageTests.Basics.BuildersWithNameTemplateScenario.Thermostat buildingInstance)
	Composition ..> Webcam : Webcam InstallWebcam(Pure.DI.UsageTests.Basics.BuildersWithNameTemplateScenario.Webcam buildingInstance)
	Webcam *--  Guid : Guid
	Webcam *--  WiFi : INetwork
	Thermostat *--  WiFi : INetwork
	namespace Pure.DI.UsageTests.Basics.BuildersWithNameTemplateScenario {
		class Composition {
		<<partial>>
		+IDevice InstallIDevice(Pure.DI.UsageTests.Basics.BuildersWithNameTemplateScenario.IDevice buildingInstance)
		+Thermostat InstallThermostat(Pure.DI.UsageTests.Basics.BuildersWithNameTemplateScenario.Thermostat buildingInstance)
		+Webcam InstallWebcam(Pure.DI.UsageTests.Basics.BuildersWithNameTemplateScenario.Webcam buildingInstance)
		}
		class IDevice {
				<<interface>>
		}
		class INetwork {
			<<interface>>
		}
		class Thermostat {
				<<record>>
			+INetwork Network
		}
		class Webcam {
				<<record>>
			+INetwork Network
			+SetId(Guid id) : Void
		}
		class WiFi {
				<<class>>
			+WiFi()
		}
	}
	namespace System {
		class Guid {
				<<struct>>
		}
		class IComparable {
			<<interface>>
		}
		class IComparableᐸGuidᐳ {
			<<interface>>
		}
		class IEquatableᐸGuidᐳ {
			<<interface>>
		}
		class IFormattable {
			<<interface>>
		}
		class IParsableᐸGuidᐳ {
			<<interface>>
		}
		class ISpanFormattable {
			<<interface>>
		}
		class ISpanParsableᐸGuidᐳ {
			<<interface>>
		}
		class IUtf8SpanFormattable {
			<<interface>>
		}
		class IUtf8SpanParsableᐸGuidᐳ {
			<<interface>>
		}
	}

Loading