What is the best practice for an interface to a library

Question

I'm currently implementing a library in C#. My main class is called Foo. It implements the interface IFoo. I'm using the Dependency Injection library from Microsoft to inject this and other dependencies. My idea was to add the following code to my service provider class:

public static IFoo GetFoo()
{
  return ServiceProvider.GetService<IFoo>();
}

So the integrator does not have to know how to build an instance of Foo and inject the dependencies to it. And the integrator only knows the interface.

I done some research about this topic but I do not find any standards or best practices about this topic.

So my question is: are there any standards or best practices and does my solution have any disadvantages?

Answer 1

The quite common approach is to provide a method, usually in namespace like MyLyb.Extensions.DependencyInjection (sometimes even in Microsoft.Extensions.DependencyInjection though you should have very specific name in this case) which can be put into a different library, depending on the use case. And then expose the registration:

namespace MyLyb.Extensions.DependencyInjection;
public static class MyLybRegistrationExtensions
{
    // possibly add another parameter to provide/setup the SDK settings
    public static IServiceCollection AddMyLib(this IServiceCollection services)
    {
        // registration goes here
        return services;
    }
}

Also this method can expose action to set the options for the library - public static IServiceCollection AddMyLib(this IServiceCollection services, Action<MyLibOptions> setOptions = null)

For example - AutoMapper's integration with ASP.NET Core.