Support discovery of internal types in AddGatewayHandlers

[chespina]

Description

Currently, GatewayHandlerServiceCollectionExtensions.AddGatewayHandlers appears to be restricted to only scanning public types within the given assembly. It's a popular design choice to leave types as internal. Without support for internal type discovery, the developer must manually register each handler, which can be tedious and unnecessary boilerplate.

[KubaZ2]

Hi @chespina, thanks for the suggestion.

Is there any reason you don't want the handlers to be public? I am not a fan of registering non-public types with AddGatewayHandlers, that would mean the library accesses types it would normally have no access to if it referenced your assembly. Also internal means internal after all, a user may not expect an internal type to be loaded automatically.
I have written this example of how to workaround this issue:

var builder = Host.CreateApplicationBuilder(args);

var services = builder.Services;

services.AddDiscordGateway();

foreach (var type in typeof(Program).Assembly.GetTypes())
{
    if (typeof(IGatewayHandler).IsAssignableFrom(type))
        services.AddSingleton(typeof(IGatewayHandler), type);
}

var app = builder.Build();

await app.RunAsync();

internal class ReadyHandler(ILogger<ReadyHandler> logger) : IReadyGatewayHandler
{
    public ValueTask HandleAsync(ReadyEventArgs args)
    {
        logger.LogInformation("Logged in as: {}", args.User.Username);
        return default;
    }
}

AddGatewayHandler does not expose an overload allowing the Type of the handler to be specified so you need to add it directly to make it work for now. I will probably add the missing overload soon.

Also note that the NetCord's internal implementation is a bit more complicated, so you may need to adjust this example.

Does this solution work for you?

[chespina]

Yes. I actually wanted to point out a common problem with methods that add automatic type discovery. Popular libraries usually include a flag/bool parameter that lets you define whether to include internal types in searches, but I didn't see one in NetCord. Even so, I understand your design decision regarding internal types. Your solution works! Thanks.