Unsealed RelayCommand

[czmirek]

Hello,

I'm building an Android app with .MAUI with .NET 7 and I wanted to try the behavior of FlowExceptionsToTaskScheduler boolean inside the RelayCommandAttribute which I've just discovered today.

Few months back I couldn't find a way to fire TaskScheduler.UnobservedTaskException or Android.Runtime.AndroidEnvironment.UnhandledExceptionRaiser. Any exception just crashes the application, only my own try...catch blocks can prevent that.

But now setting FlowExceptionsToTaskScheduler = true works just great and the exception goes to UnobservedTaskException.

    [RelayCommand] //crashes the app, does not go to UnobservedTaskException
    async Task CrashingMethod1()
    {
        throw new Exception();
    }

    [RelayCommand(FlowExceptionsToTaskScheduler = true)] //goes to UnobservedTaskException event
    async Task CrashingMethod2()
    {
        throw new Exception();
    }

Excellent!

FlowExceptionsToTaskScheduler is false by default...but I want it to be true by default everywhere, I really need to avoid crashing of the app at all costs, showing some error dialogs instead.

Having [RelayCommand(FlowExceptionsToTaskScheduler = true)] everywhere works...but it's kinda ugly.

So let's just make my own class, something like GuardedRelayCommandAttribute which extends the RelayCommandAttribute and sets the property to true by default on initialization.

...except I cannot. Because RelayCommandAttribute is sealed.

Thoughts?

[kmgallahan]

You are using RelayCommandAttribute, which uses Roslyn source generation to create AsyncRelayCommands.

Even if it were unsealed so you could use inheritance, it would no longer be picked up by the source generation logic.

Instead, you should propose that a configuration option should be provided to set the default value used during source generation.