Exporting

ServiceDescriptor can be exported as field.

public class Module1
{
    /// <summary>Singleton</summary>
    public static Module1 Instance { get; } = new();

    /// <summary>Export ServiceDescriptor</summary>
    public ServiceDescriptor Ids = ServiceDescriptor.Singleton<IList<string>>(new string[] { "id-4", "id-5", "id-6" });
    /// <summary>Export pre-build action (Invoked only with IHostBuilder)</summary>
    public Action<IServiceCollection> PreBuildAction = (IServiceCollection sc) => WriteLine("IService Pre-Build");
    /// <summary>Export post-build action (Invoked only with IHostBuilder)</summary>
    public Func<IServiceProvider, IServiceProvider> PostBuildAction = (IServiceProvider sp) => { WriteLine("IService Post-Build"); return sp; };
}

[ServiceDescriptor<T>(scope)] can be attached on classes to be exported. The module must inherit IImportsAssembly<Module> to indicate that the assembly is to be scanned for exported classes.

[ServiceDescriptor<IList<string>>(ServiceScope.Singleton)]
public class Ids : List<string>
{
    public Ids() { Add("id-1"); Add("id-2"); Add("id-3"); }
}

public class Module2 : IImportsAssembly<Module2>
{
    public static Module2 Instance { get; } = new();
}

Importing to IServiceCollection

ServiceDescriptorContainer.ModuleImportCached[module] scans ServiceDescriptors from module instance.

// Initialize service descriptors
IServiceCollection serviceCollection = new ServiceCollection();
ServiceDescriptorContainer.ModuleImportCached[Module1.Instance].WriteTo(serviceCollection);
ServiceDescriptorContainer.ModuleImportCached[Module2.Instance].WriteTo(serviceCollection);
// Build DI
IServiceProvider serviceProvider = serviceCollection.BuildServiceProvider();
// Query service
IEnumerable<string> ids = serviceProvider.GetRequiredService<IEnumerable<IList<string>>>().SelectMany(a => a);
WriteLine(string.Join(", ", ids)); // "id-4, id-5, id-6, id-1, id-2, id-3"

ModuleImportServiceDescriptor.Cached[module] scans ServiceDescriptors from module instance. This method does not follow dependencies.

ServiceDescriptor[] serviceDescriptors = ModuleImportServiceDescriptor.Cached[Module1.Instance];

Importing to IHostBuilder

HostingContainer.ModuleImportCached[module] scans ServiceDescriptors from module instance.

// Initialize host builder
IHostBuilder hostBuilder = new HostBuilder();
hostBuilder.UseServiceProviderFactory(HostServiceProviderFactory.Instance);
HostingContainer.ModuleImportCached[Module1.Instance].WriteTo(hostBuilder);
HostingContainer.ModuleImportCached[Module2.Instance].WriteTo(hostBuilder);
// Build host
IHost host = hostBuilder.Build();
// Query service
IEnumerable<string> ids = host.Services.GetRequiredService<IEnumerable<IList<string>>>().SelectMany(a => a);
WriteLine(string.Join(", ", ids)); // "id-4, id-5, id-6, id-1, id-2, id-3"

Full Example

Full example

using Avalanche.DependencyInjection;
using Avalanche.Hosting;
using Avalanche.Module;
using Avalanche.Utilities;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using static System.Console;

public class servicecollection
{
    public static void Run()
    {
        {
            // <01>
            // Initialize service descriptors
            IServiceCollection serviceCollection = new ServiceCollection();
            ServiceDescriptorContainer.ModuleImportCached[Module1.Instance].WriteTo(serviceCollection);
            ServiceDescriptorContainer.ModuleImportCached[Module2.Instance].WriteTo(serviceCollection);
            // Build DI
            IServiceProvider serviceProvider = serviceCollection.BuildServiceProvider();
            // Query service
            IEnumerable<string> ids = serviceProvider.GetRequiredService<IEnumerable<IList<string>>>().SelectMany(a => a);
            WriteLine(string.Join(", ", ids)); // "id-4, id-5, id-6, id-1, id-2, id-3"
            // </01>
        }
        {
            // <02>
            ServiceDescriptor[] serviceDescriptors = ModuleImportServiceDescriptor.Cached[Module1.Instance];
            // </02>
        }
        {
            // <11>
            // Initialize host builder
            IHostBuilder hostBuilder = new HostBuilder();
            hostBuilder.UseServiceProviderFactory(HostServiceProviderFactory.Instance);
            HostingContainer.ModuleImportCached[Module1.Instance].WriteTo(hostBuilder);
            HostingContainer.ModuleImportCached[Module2.Instance].WriteTo(hostBuilder);
            // Build host
            IHost host = hostBuilder.Build();
            // Query service
            IEnumerable<string> ids = host.Services.GetRequiredService<IEnumerable<IList<string>>>().SelectMany(a => a);
            WriteLine(string.Join(", ", ids)); // "id-4, id-5, id-6, id-1, id-2, id-3"
            // </11>
        }
    }


    // <98>
    public class Module1
    {
        /// <summary>Singleton</summary>
        public static Module1 Instance { get; } = new();

        /// <summary>Export ServiceDescriptor</summary>
        public ServiceDescriptor Ids = ServiceDescriptor.Singleton<IList<string>>(new string[] { "id-4", "id-5", "id-6" });
        /// <summary>Export pre-build action (Invoked only with IHostBuilder)</summary>
        public Action<IServiceCollection> PreBuildAction = (IServiceCollection sc) => WriteLine("IService Pre-Build");
        /// <summary>Export post-build action (Invoked only with IHostBuilder)</summary>
        public Func<IServiceProvider, IServiceProvider> PostBuildAction = (IServiceProvider sp) => { WriteLine("IService Post-Build"); return sp; };
    }
    // </98>

    // <99>
    [ServiceDescriptor<IList<string>>(ServiceScope.Singleton)]
    public class Ids : List<string>
    {
        public Ids() { Add("id-1"); Add("id-2"); Add("id-3"); }
    }

    public class Module2 : IImportsAssembly<Module2>
    {
        public static Module2 Instance { get; } = new();
    }
    // </99>

}