Musing on supplying sample data in a non-sucky way (with ReactiveUI)

MainWindow.cs

using ReactiveUI;

namespace WpfApplication1
{
    public class DesignMainViewModel : MainViewModel
    {
        public DesignMainViewModel()
        {
            UserName = "shiftkey";
        }
    }

    public class MainViewModel : ReactiveObject
    {
        [DesignData("shiftkey")]
        public string UserName { get; set; }
    }

    public partial class MainWindow : IViewFor<MainViewModel>
    {
        public MainWindow()
        {
            InitializeComponent();

            // 1. keep sample data on the viewmodel
            // PRO: keeps view unclutted
            // CON: makes viewmodel cluttered
            // CON: attributes take object parameter - not as type-safe
            // CON: this sucks for things like collections or anything complex
            this.Bind(ViewModel, vm => vm.UserName);

            // 2. extension methods off Bind/BindOneWay
            // PRO: type-checking
            // PRO: keeps design data close to UI
            // CON: this still sucks for things like collections
            this.Bind(ViewModel, vm => vm.UserName)
                .WithDesignTime("shiftkey");
                
            // 2a. slightly different syntax perhaps?
            this.Bind(ViewModel, vm => vm.UserName, "shiftkey");
            
            // 3. specify design data once after all Bind/BindOneWay
            // PRO: keep data separate from ViewModel
            // PRO: no stuffing around in the the awful d: space 
            // PRO: more friendly for complex properties like collections
            // CON: yay over-abstraction
            // CON: needing to keep your design VM and runtime VM in sync (I use interfaces but it's not great)

            // Q: perhaps this could lean on conventions (use DesignFooViewModel for FooViewModel)
            // and not even require an explicit call
            this.BindDesignData<DesignMainViewModel>();
        }

        // and the rest of the code ... 
    }
}