Rollcall

Provides support for named service registration through the use of extension methods on the IServiceCollection interface, and retrieval of registered service by name using a factory.

Installing Rollcall

Rollcall is available on NuGet via:

Install-Package Rollcall.Extensions.Microsoft.DependencyInjection

Or via the .NET CLI:

dotnet add package Rollcall.Extensions.Microsoft.DependencyInjection

Or via NuGet Packager Manager in Visual Studio

Direct link to Rollcall on NuGet: https://www.nuget.org/packages/Rollcall.Extensions.Microsoft.DependencyInjection/

How to use Rollcall

Configuring the dependency injection container

Use the AddNamedService to register the interface, with the various named implementations

host = Host.CreateDefaultBuilder()
    .ConfigureServices((context, services) => services
    .AddNamedService<IFileUploader>(builder => builder
        .AddTransient("aws", typeof(AWSUploader))
        .AddTransient("azure", typeof(AzureUploader))
        .AddTransient("ftp", typeof(FTPUploader))
    )
).Build();

Retrieving a named service

Using IRollcallProvider

Inject IRollcallProvider into the relevant class, and use the GetService method to retrieve the implementation by name.

public class RollcallHandler
{
    private readonly IRollcallProvider<IFileUploader> _provider;

    public RollcallHandler(IRollcallProvider<IFileUploader> provider)
    {
        _provider = provider;
    }

    public void Execute()
    {
        var providerName = "aws";

        var uploader = _provider.GetService(providerName);
        uploader.UploadFile();
    }
}

Using IServiceProvider

Use the provided extension method in IServiceProvider.

public class RollcallHandler
{
    private readonly IServiceProvider _serviceProvider;

    public RollcallHandler(IServiceProvider serviceProvider)
    {
        _serviceProvider = serviceProvider;
    }

    public void Execute()
    {
        var providerName = "azure";

        var uploader = _serviceProvider.GetService<IFileUploader>(providerName);
        uploader.UploadFile();
    }
}

Benchmarks

There are a variety of ways to handle multiple implementations of the same interface using the default .NET dependency injection implementation.
Depending on the use case and the complexity of your implementations (e.g. the number of dependencies the implementations have) Rollcall might not be the best solution.

See this blog post with the various methods of handling multiple implementations, as well as some simple benchmarks.