IHandlerCast

IHandlerCast indicates that handler is a type-cast of an underlying handler.

/// <summary>Indicates that the service is a decoration that type-casts <see cref="IHandlerBase"/> interfaces, and decorates no other aspect of the source.</summary>
public interface IHandlerCast : IHandlerDecoration, IHandlerBase { }

IHandlerCastable is interface for handlers implementations that can override type-cast behaviour.

/// <summary>Interface for handlers that can override type-cast behaviour.</summary>
public interface IHandlerCastable
{
    /// <summary>Try cast the handler into <see cref="IHandler"/>. </summary>
    bool TryCast([NotNullWhen(true)] out IHandler casted);
    /// <summary>Try cast the handler into <see cref="IHandler"/>. </summary>
    bool TryCastAsync([NotNullWhen(true)] out IHandlerAsync casted);

    /// <summary>Try cast the handler into <see cref="IHandler{Request, Response}"/>. </summary>
    bool TryCast<Request, Response>([NotNullWhen(true)] out IHandler<Request, Response> casted) where Request : notnull;
    /// <summary>Try cast the handler into <see cref="IHandlerAsync{Request, Response}"/>. </summary>
    bool TryCastAsync<Request, Response>([NotNullWhen(true)] out IHandlerAsync<Request, Response> casted) where Request : notnull;
}

Handler can be casted into other request response generic type parameters.

// Create generics handler
IHandler consoleLogger = new ConsoleLogger();
// Cast to IHandler<object, object>
consoleLogger.TryCast(out IHandler<object, object>? castedHandler);

IServiceBase.AsHandler() casts a service into IHandlerBase.

// Create service
IService service = Services.Create(ConverterHandlers.Instance);
// Cast to handler
IHandler handler = service.AsHandler();

IEntryProviderBase.AsHandler() casts entry provider into IHandlerBase.

// Create entry provider
IEntryProvider entryProvider = (IEntryProvider)Services.Create(ConverterHandlers.Instance);
// Cast to handler
IHandlerBase handler = Handlers.EntryProvider(entryProvider);

If handler implements IHandlerCastable, it can override in casting behaviour.

public class Handler21 : IHandler, IHandlerCastable
{
    public void Handle<Request, Response>(IQuery<Request, Response> query) where Request : notnull
        => Console.WriteLine(query.Response);

    public bool TryCast([NotNullWhen(true)] out IHandler casted) { casted = null!; return false; }
    public bool TryCast<Request, Response>([NotNullWhen(true)] out IHandler<Request, Response> casted) where Request : notnull { casted = null!; return false; }
    public bool TryCastAsync([NotNullWhen(true)] out IHandlerAsync casted) { casted = null!; return false; }
    public bool TryCastAsync<Request, Response>([NotNullWhen(true)] out IHandlerAsync<Request, Response> casted) where Request : notnull { casted = null!; return false; }
}

Full Example

Full example

using System;
using System.Diagnostics.CodeAnalysis;
using Avalanche.Converter;
using Avalanche.Service;

public class handler_cast
{
    public static void Run()
    {
        {
            // <01>
            // Create generics handler
            IHandler consoleLogger = new ConsoleLogger();
            // Cast to IHandler<object, object>
            consoleLogger.TryCast(out IHandler<object, object>? castedHandler);
            // </01>
        }

        {
            // <02>
            // Create service
            IService service = Services.Create(ConverterHandlers.Instance);
            // Cast to handler
            IHandlerBase handler = Handlers.Service(service);
            // </02>
        }

        {
            // <03>
            // Create service
            IService service = Services.Create(ConverterHandlers.Instance);
            // Cast to handler
            IHandler handler = service.AsHandler();
            // </03>
        }

        {
            // <04>
            // Create entry provider
            IEntryProvider entryProvider = (IEntryProvider)Services.Create(ConverterHandlers.Instance);
            // Cast to handler
            IHandlerBase handler = Handlers.EntryProvider(entryProvider);
            // </04>
        }
        {
            // <05>
            // Create entry provider
            IEntryProvider entryProvider = (IEntryProvider)Services.Create(ConverterHandlers.Instance);
            // Cast to handler
            IHandler handler = entryProvider.AsHandler();
            // </05>
        }
    }

    // <98>
    public class ConsoleLogger : IHandler
    {
        public void Handle<Request, Response>(IQuery<Request, Response> query) where Request : notnull
            => Console.WriteLine(query.Response);
    }
    // </98>

    // <99>
    public class Handler21 : IHandler, IHandlerCastable
    {
        public void Handle<Request, Response>(IQuery<Request, Response> query) where Request : notnull
            => Console.WriteLine(query.Response);

        public bool TryCast([NotNullWhen(true)] out IHandler casted) { casted = null!; return false; }
        public bool TryCast<Request, Response>([NotNullWhen(true)] out IHandler<Request, Response> casted) where Request : notnull { casted = null!; return false; }
        public bool TryCastAsync([NotNullWhen(true)] out IHandlerAsync casted) { casted = null!; return false; }
        public bool TryCastAsync<Request, Response>([NotNullWhen(true)] out IHandlerAsync<Request, Response> casted) where Request : notnull { casted = null!; return false; }
    }
    // </99>
}