Services

A service is any module-owned class you want registered in DI. Annotate it with [Service] and the generator emits the registration — you never add it to a hand-written AddXyz() method.

using Elarion.Abstractions;

namespace MyApp.Application.Modules.Clients.Services;

public interface IClientNumberGenerator {
    string Next();
}

[Service(typeof(IClientNumberGenerator))]
public sealed class ClientNumberGenerator : IClientNumberGenerator {
    public string Next() => "C-001";
}

When [assembly: UseElarion] or [assembly: GenerateModuleServices] is present, Elarion emits Add{ServiceName}Service() and aggregates them into Add{ModuleName}Services().

Contract resolution

The generator decides which contract(s) to register against using these rules, in order:

1. If explicit contracts are given in [Service(typeof(...))], those are used.
2. Otherwise, directly implemented interfaces are used.
3. Otherwise, the implementation type itself is registered.

Lifetime

The default scope is Scoped. Override it with the Scope property:

[Service(typeof(IClock), Scope = ServiceScope.Singleton)]
public sealed class SystemClock : IClock { /* ... */ }

ServiceScope has Scoped, Singleton, and Transient.

Hosted services

A class that implements IHostedService or derives from BackgroundService is auto-detected as a hosted service. Hosted services must be singletons — the generator emits an error for scoped/transient hosted services.

Generated hosted registration follows the standard pattern, registering the concrete service and an IHostedService forwarder:

services.AddSingleton<IMailboxPollingService, MailboxPollingService>();
services.AddSingleton<IHostedService>(
    sp => (IHostedService)sp.GetRequiredService<IMailboxPollingService>());

To keep lifecycle methods hidden from ordinary consumers, implement IHostedService explicitly:

public interface IMailboxPollingService {
    Task PollNowAsync(CancellationToken ct);
}

[Service(typeof(IMailboxPollingService), Scope = ServiceScope.Singleton)]
public sealed class MailboxPollingService : IMailboxPollingService, IHostedService {
    Task IHostedService.StartAsync(CancellationToken ct) => Task.CompletedTask;
    Task IHostedService.StopAsync(CancellationToken ct) => Task.CompletedTask;

    public Task PollNowAsync(CancellationToken ct) => Task.CompletedTask;
}