Custom IOptions service

Create a new console application and add packages for DI and Hosting:

dotnet new console
dotnet add package Microsoft.Extensions.Hosting
dotnet add package Microsoft.Extensions.DependencyInjection

Add a class for the new object, and an extension method for registering it with dependency injection:

class Foo
{
	public string Name { get; set; } = "Not set";
}

static class FooExtensions
{
	public static IServiceCollection AddFoo(
		this IServiceCollection services, Action<Foo>? options = null)
	{
		return services.Configure(options ?? (x => { }));
	}
}

Build your hosted service:

partial class Program : BackgroundService
{
	private readonly Foo _foo;

	public Program(IOptions<Foo> foo)
	{
		_foo = foo.Value;
	}

	protected override Task ExecuteAsync(CancellationToken stoppingToken)
	{
		Console.WriteLine(_foo.Name);
		Environment.Exit(0);
		return Task.CompletedTask;
	}
}

Build your application entry point, and you can use the options pattern to configure your custom object while registering it:

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Options;

await Host.CreateDefaultBuilder(args)
	.ConfigureServices((HostExecutionContext, services) =>
	{
		// services.AddFoo();
		// OR
		services.AddFoo(options =>
		{
			options.Name = "Hello";
		});

		services.AddHostedService<Program>();
	})
	.Build()
	.RunAsync();

IOptions is a singleton, so the Foo object will only be generated once.

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