[Enhancement] Generic EventToCommandBehavior

[pictos]

Summary

Today with our current EventToCommandBehavior implementation we can see some issue using strongly type arguments with Command<T> the workaround today is using T as object and that's a kinda bad-sh thing to do.
If we have an EventToCommandBehavior<TType> that inherits from our EventToCommandBehavior we will be able to force the parameter to be the TType and doesn't crash the application.

An example of this issue can be seen here #950

API Changes

Here's the full implementation so far.

public class EventToCommandBehavior<TType> : EventToCommandBehavior
{
    protected override void OnTriggerHandled(object sender = null, object eventArgs = null)
    {
	    var parameter = CommandParameter
		    ?? EventArgsConverter?.Convert(eventArgs, typeof(object), null, null)
		    ?? eventArgs;
    
	    if (parameter.GetType() != typeof(TType))
	    {
		    parameter = null; // not sure if this a good approach, but nulling it we prevent an InvalidCastException (I suppose)
		    parameter = Convert.ChangeType(parameter, typeof(TType));
	    }
    
	    var command = Command;
	    if (command?.CanExecute(parameter) ?? false)
		    command.Execute(parameter);
    }
}

Intended Use Case

Make this scenario works

Coffee selectedCoffee;
public Coffee SelectedCoffee
{
    get => selectedCoffee;
    set => SetProperty(ref selectedCoffee, value);
}

async Task Selected(Coffee coffee)
{
    if (coffee == null)
        return;

    await Application.Current.MainPage.DisplayAlert("Selected", coffee.Name, "OK");
    SelectedCoffee = null;
}

On XAML the usage will be

<xct:EventToCommandBehavior
    x:TypeArguments="model:Coffee"
    Command="{Binding SelectedCommand}"
    EventArgsConverter="{StaticResource ItemSelectedEventArgsConverter}"
    EventName="ItemSelected" />

Who Will Do The Work?

• I am willing to take this on myself
• Just putting this out there for someone to pick up

[pictos]

@jamesmontemagno I went out to cycle I came up with this implementation, and it works very well so far. Let me know what do you think.

Also, @AndreiMisiukevich , @sthewissen, and @jsuarezruiz can you share your thoughts on this?

[AndreiMisiukevich]

@pictos I think you did a good job on the investigation) And I like this solution

[jamesmontemagno]

I guess if eventArgs are null then just pass it null to Execute?

[pictos]

@jamesmontemagno

I guess if eventArgs are null then just pass it null to Execute?

But the eventArgs isn't null, it will be the event EventArgs, in that case, will be ItemSelectedEventArgs. If was the Tapped event the eventArgs will be ItemTappedEventArgs