Microsoft.Extensions.DependencyInjection Factory

Microsoft.Extensions.DependencyInjection_Factory.linq

<Query Kind="Program">
  <NuGetReference>Microsoft.Extensions.DependencyInjection</NuGetReference>
  <NuGetReference>Microsoft.Extensions.DependencyInjection.Abstractions</NuGetReference>
  <Namespace>Microsoft.Extensions.DependencyInjection</Namespace>
  <Namespace>Microsoft.Extensions.DependencyInjection.Extensions</Namespace>
</Query>

void Main()
{
	var sc = new ServiceCollection();
	sc.AddSingleton<Test>();
	sc.AddSingleton<TestLazy>();
	sc.AddFactory<Car, CarFactory>();
	sc.AddFactory<Airplane, AirplaneFactory>();
	sc.BuildServiceProvider().GetService<Test>().Dump();	
	sc.BuildServiceProvider().GetService<TestLazy>().Dump();	
}

public static class ServiceCollectionExtensions
{
	public static void AddFactory<TImplementation, TFactory>(this IServiceCollection services)
		where TFactory : class, IFactory<TImplementation>
		where TImplementation : class
	{
		services.AddSingleton<IFactory<TImplementation>, TFactory>();
		services.AddSingleton<TImplementation>(x => 
			x.GetRequiredService<IFactory<TImplementation>>().Create()
		);
		services.AddSingleton<Func<TImplementation>>(x => () => x.GetRequiredService<IFactory<TImplementation>>().Create());
	}
}

public class Test
{
	public Test(Car aa, Airplane bb)
	{
		Car = aa;
		Airplane = bb;
	}
	
	public Car Car {get; }
	public Airplane Airplane {get; }
}

public class TestLazy
{
	public TestLazy(Func<Car> aa, Airplane bb)
	{
		Car = aa();
		Airplane = bb;
	}

	public Car Car { get; }
	public Airplane Airplane { get; }
}

public interface IFactory<T>
{
	T Create();
}

public class Car
{
	public Car(string name)
	{
		Name = name;
	}
	public string Name { get; }
}

public class CarFactory : IFactory<Car>
{
	public Car Create() => new Car("aaa");
}

public class Airplane
{
	public Airplane(string name)
	{
		Name = name;
	}
	public string Name { get; }
}

public class AirplaneFactory : IFactory<Airplane>
{
	public Airplane Create() => new Airplane("Airplaneeeeeee");
}