Add CommandExceptionHandler

[JKamsker]

Reason:
I need a way of handling exceptions while having the typeresolver around. (To log to an implementation of ILogger for e.g)
Unfortunately, the existing exceptionhandler does not provide a way of accessing the ITypeResolver

Usage:

public class GenericExceptionHandler : ICommandExceptionHandler
{
    // You can inject services here
    public GenericExceptionHandler()
    {
        
    }

        public bool Handle(CommandExceptionArgs args)
        {
            AnsiConsole.MarkupLine($"[red]{args.Exception.Message}[/]");
            return true;
        }
}

public class CommandGenericExceptionHandler : ICommandExceptionHandler<MyCommand>
{
    // You can inject services here
    public CommandGenericExceptionHandler()
    {
        
    }

        public bool Handle(CommandExceptionArgs args)
        {
            AnsiConsole.MarkupLine($"[red]{args.Exception.Message}[/]");
            return true;
        }
}

Then register them during startup:

//...
services.AddTransient<ICommandExceptionHandler, GenericExceptionHandler>();
services.AddTransient< ICommandExceptionHandler<MyCommand>, CommandGenericExceptionHandler>();

//...
var app = new CommandApp(new TypeRegistrar(services));

[nils-a]

Wouldn't it be easier to add the current ITypeResolver to the existing ErrorHandling?

[JKamsker]

@nils-a Apologies, I'm having a bit of difficulty understanding what you're suggesting. Could you please explain it?

OT: Force pushed because i wanted a cleaner diff. The CommandExecutor appearantly is in mixed mode (LF & CRLF). vscode messes it up.

[nils-a]

@JKamsker the currently existing way to handle exceptions is:

var app = new CommandApp<DefaultCommand>();
app.Configure(config =>
{
    config.SetExceptionHandler(err =>
    {
        AnsiConsole.WriteException(err);
        // or whatever....
    });
});

I don't quite like the idea of adding another, different way to do exception handling.

So: If you need the ITypeResolver while handling exceptions, my proposal was to add the ITypeResolver to the exception handler like this:

var app = new CommandApp<DefaultCommand>();
app.Configure(config =>
{
    config.SetExceptionHandler((err, resolver) =>
    {
        var console = (IAnsiConsole)resolver.Resolve(typeof(IAnsiConsole));
        console.WriteException(err);
        // or whatever....
    });
});

[JKamsker]

@nils-a Oh yea, that seems like a neat idea! Why haven't i thought about this? 😅
Would adding an overload like SetExceptionHandler<TCommand> be acceptable?

[nils-a]

Would adding an overload like SetExceptionHandler be acceptable?

Hm. Do you really need different handlers for different Commands? I have the feeling this would make things rather complicated.
Wouldn't it be easier, in that case, to create your own ICommand that is capable of handling exceptions?

[FrankRay78]

Superseded by #1411.