Delegates

Handlers.Delegate(delegate) converts a delegate into IHandlerBase.

// Create sum calculator
Delegate sumCalculator = (IQuery<(int, int), int> q) => q.Response.SetValue(q.Request.Item1 + q.Request.Item2);
// Cast to handler
IHandlerBase handler = Handlers.Delegate(sumCalculator);
// Create service
IService<(int, int), int> service = Services.Create<(int, int), int>(handler);

Handlers.Action(delegate) converts an Action<IQuery<Request, Response>> into IHandler.

// Create sum calculator
Action<IQuery<(int, int), int>> sumCalculator = q => q.Response.SetValue(q.Request.Item1 + q.Request.Item2);
// Cast to handler
IHandler<(int, int), int> handler = Handlers.Action(sumCalculator);
// Create service
IService<(int, int), int> service = Services.Create<(int, int), int>(handler);

[Order(value)] can be placed on delegate for evaluation order.

// Create sum calculator
Delegate sumCalculator = [Order(100)] (IQuery<(int, int), int> q) => q.Response.SetValue(q.Request.Item1 + q.Request.Item2);
// Cast to handler
IHandlerBase handler = Handlers.Delegate(sumCalculator);

Order can also be passed as second parameter 'order:'.

// Create sum calculator
Delegate sumCalculator = (IQuery<(int, int), int> q) => q.Response.SetValue(q.Request.Item1 + q.Request.Item2);
// Cast to handler
IHandlerBase handler = Handlers.Delegate(sumCalculator, order: 100);

Action<IQuery> handles all request types.

// Create query logger
Action<IQuery> queryLogger = q => Console.WriteLine(q.Response);
// Cast to handler
IHandler loggerHandler = Handlers.Action(queryLogger, order: long.MaxValue);

Func<IQuery<Request, Response>, Task> and Func<IQuery, Task> handles asynchronously.

// Create async handler
Func<IQuery<string, string>, Task> urlDownloader =
    async q => q.Response.SetValue(await new WebClient().DownloadStringTaskAsync(q.Request));
// Cast to handler
IHandlerAsync<string, string> handler = Handlers.FuncAsync(urlDownloader, order: 250);
// Create service
IService<string, string> service = Services.Create<string, string>(handler);
// Download
string content = await service.GetRequiredAsync("http://avalanche.fi");
// Print html
Console.WriteLine(content);

If delegate is provided to service construction as is, it's automatically casted into IHandlerBase.

// Create async handler
Func<IQuery<string, string>, Task> urlDownloader =
    async q => q.Response.SetValue(await new WebClient().DownloadStringTaskAsync(q.Request));
// Create service
IService<string, string> service = Services.Create<string, string>(urlDownloader);
// Download
string content = await service.GetRequiredAsync("http://avalanche.fi");
// Print html
Console.WriteLine(content);

Full Example

Full example

#pragma warning disable SYSLIB0014 
using System;
using System.Net;
using System.Threading.Tasks;
using Avalanche.Module;
using Avalanche.Service;
using Avalanche.Service.Internal;
using static System.Console;

public class handler_delegates
{
    public static async Task Run()
    {
        {
            // <01>
            // Create sum calculator
            Delegate sumCalculator = (IQuery<(int, int), int> q) => q.Response.SetValue(q.Request.Item1 + q.Request.Item2);
            // Cast to handler
            IHandlerBase handler = Handlers.Delegate(sumCalculator);
            // Create service
            IService<(int, int), int> service = Services.Create<(int, int), int>(handler);
            // </01>
        }
        {
            // <02>
            // Create sum calculator
            Action<IQuery<(int, int), int>> sumCalculator = q => q.Response.SetValue(q.Request.Item1 + q.Request.Item2);
            // Cast to handler
            IHandler<(int, int), int> handler = Handlers.Action(sumCalculator);
            // Create service
            IService<(int, int), int> service = Services.Create<(int, int), int>(handler);
            // </02>
        }
        {
            // <03A>
            // Create sum calculator
            Delegate sumCalculator = [Order(100)] (IQuery<(int, int), int> q) => q.Response.SetValue(q.Request.Item1 + q.Request.Item2);
            // Cast to handler
            IHandlerBase handler = Handlers.Delegate(sumCalculator);
            // </03A>
            // Print order
            WriteLine(((DelegateHandler)handler).Order);
            // Create service
            IService<(int, int), int> service = Services.Create<(int, int), int>(handler);
        }
        {
            // <03B>
            // Create sum calculator
            Delegate sumCalculator = (IQuery<(int, int), int> q) => q.Response.SetValue(q.Request.Item1 + q.Request.Item2);
            // Cast to handler
            IHandlerBase handler = Handlers.Delegate(sumCalculator, order: 100);
            // </03B>
            // Create service
            IService<(int, int), int> service = Services.Create<(int, int), int>(handler);
        }

        {
            // <04>
            // Create query logger
            Action<IQuery> queryLogger = q => Console.WriteLine(q.Response);
            // Cast to handler
            IHandler loggerHandler = Handlers.Action(queryLogger, order: long.MaxValue);
            // </04>
            // Create service
            IService service = Services.Create((ServiceHandlers.Instance, loggerHandler));
            // Get type
            Type? type = service.Get<TypeRequest, Type>("System.String");
            // Logger handler prints "Entry<Type>(Value, Cached, System.String, , Default)" on query
        }

        {
            // <05>
            // Create async handler
            Func<IQuery<string, string>, Task> urlDownloader =
                async q => q.Response.SetValue(await new WebClient().DownloadStringTaskAsync(q.Request));
            // Cast to handler
            IHandlerAsync<string, string> handler = Handlers.FuncAsync(urlDownloader, order: 250);
            // Create service
            IService<string, string> service = Services.Create<string, string>(handler);
            // Download
            string content = await service.GetRequiredAsync("http://avalanche.fi");
            // Print html
            Console.WriteLine(content);
            // </05>
        }

        {
            // <06>
            // Create async handler
            Func<IQuery<string, string>, Task> urlDownloader =
                async q => q.Response.SetValue(await new WebClient().DownloadStringTaskAsync(q.Request));
            // Create service
            IService<string, string> service = Services.Create<string, string>(urlDownloader);
            // Download
            string content = await service.GetRequiredAsync("http://avalanche.fi");
            // Print html
            Console.WriteLine(content);
            // </06>
        }
    }
}
#pragma warning restore SYSLIB0014