Simple WPF RadioButton Binding?

Question

What is the simplest way to bind a group of 3 radiobuttons to a property of type int for values 1, 2, or 3?

Answer 1

I created an attached property based on Aviad's Answer which doesn't require creating a new class

public static class RadioButtonHelper
{
    [AttachedPropertyBrowsableForType(typeof(RadioButton))]
    public static object GetRadioValue(DependencyObject obj) => obj.GetValue(RadioValueProperty);
    public static void SetRadioValue(DependencyObject obj, object value) => obj.SetValue(RadioValueProperty, value);
    public static readonly DependencyProperty RadioValueProperty =
        DependencyProperty.RegisterAttached("RadioValue", typeof(object), typeof(RadioButtonHelper), new PropertyMetadata(new PropertyChangedCallback(OnRadioValueChanged)));

    private static void OnRadioValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is RadioButton rb)
        {
            rb.Checked -= OnChecked;
            rb.Checked += OnChecked;
        }
    }

    public static void OnChecked(object sender, RoutedEventArgs e)
    {
        if (sender is RadioButton rb)
        {
            rb.SetCurrentValue(RadioBindingProperty, rb.GetValue(RadioValueProperty));
        }
    }

    [AttachedPropertyBrowsableForType(typeof(RadioButton))]
    public static object GetRadioBinding(DependencyObject obj) => obj.GetValue(RadioBindingProperty);
    public static void SetRadioBinding(DependencyObject obj, object value) => obj.SetValue(RadioBindingProperty, value);

    public static readonly DependencyProperty RadioBindingProperty =
        DependencyProperty.RegisterAttached("RadioBinding", typeof(object), typeof(RadioButtonHelper), new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, new PropertyChangedCallback(OnRadioBindingChanged)));

    private static void OnRadioBindingChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is RadioButton rb && rb.GetValue(RadioValueProperty).Equals(e.NewValue))
        {
            rb.SetCurrentValue(RadioButton.IsCheckedProperty, true);
        }
    }
}

usage :