Configuration pattern and ConfigureServices

ServiceWithOptionsExample.cs

// I have a service that needs to be initialized with a FooOptions and then added to the DI container.
// I also want to have IOptions<FooOptions> in the DI container to allow injection in other methods.
// How should I write my AddFoo extension method to support this?

public void ConfigureServices(IServiceCollection services)
{
    services.AddFoo(fooOptions => 
    {
        configuration.GetSection("FooOptions").Bind(fooOptions)
        fooOptions.param = "override";
    });
}

namespace Microsoft.Extensions.DependencyInjection
{
    public static class MyFooExtensions
    {
        public static IServiceCollection AddFoo(this IServiceCollection services,
          Action<FooOptions> setupOptions)
        {
            services.Configure<FooOptions>(setupOptions);
            services.AddSingleton<IFoo>(sp =>
            {
                var options = sp.GetRequiredService<IOptions<FooOptions>>();
                return new FooFactory(options.Value);
            };
            return services;
        }
    }
}

@ericsampson That looks very similar to my suggestion, with a slight tweak. I don't think your suggestion will quite work though. Try this instead:

public void ConfigureServices(IServiceCollection services)
{
    services.AddFoo(fooOptions => 
    {
        configuration.GetSection("FooOptions").Bind(fooOptions)
        fooOptions.param = "override";
    });
}

Thanks again @andrewlock, I'll give this all a go. Really appreciate the help :)