Add converter and use it

Author: IvenBach

Rubberduck.Core/UI/Converters/ClassInstancingToBooleanConverter.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Data;
+using Rubberduck.UI.Refactorings;
+
+namespace Rubberduck.UI.Converters
+{
+    class ClassInstancingToBooleanConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            return (ClassInstancing)value == ClassInstancing.Private;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            return (bool)value
+                ? ClassInstancing.Private
+                : ClassInstancing.PublicNotCreatable;
+        }
+    }
+}

Rubberduck.Core/UI/Refactorings/ExtractInterface/ExtractInterfaceView.xaml

@@ -7,6 +7,7 @@
              mc:Ignorable="d" Height="378" Width="372">
     <UserControl.Resources>
         <converters:BoolToHiddenVisibilityConverter x:Key="BoolToHiddenVisibility" />
+        <converters:ClassInstancingToBooleanConverter x:Key="ClassInstancingToBool" />
 
         <LinearGradientBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" EndPoint="0,1" StartPoint="0,0">
             <GradientStop Color="#FFD9F4FF" Offset="0"/>
@@ -93,10 +94,11 @@
             <GroupBox Header="{Resx ResxName=Rubberduck.Resources.RubberduckUI, Key=ExtractInterface_InstancingGroupBox}"
                       Grid.Row="1" Margin="5" Padding="5">
                 <StackPanel Orientation="Horizontal">
-                    <RadioButton Content="{Resx ResxName=Rubberduck.Resources.RubberduckUI, Key=ExtractInterface_PrivateRadioButton}"
-                                 IsChecked="True" />
+                    <RadioButton x:Name="IsPrivateInstancing"
+                                 Content="{Resx ResxName=Rubberduck.Resources.RubberduckUI, Key=ExtractInterface_PrivateRadioButton}"
+                                 IsChecked="{Binding Converter={StaticResource ClassInstancingToBool}, Mode=TwoWay, Path=ClassInstancing}" />
                     <RadioButton Content="{Resx ResxName=Rubberduck.Resources.RubberduckUI, Key=ExtractInterface_PublicNotCreatableRadioButton}"
-                                 IsEnabled="{Binding IsInterfacePublicNotCreateable}"/>
+                                 IsEnabled="{Binding IsInterfacePublicNotCreateableEnabled}" />
                 </StackPanel>
             </GroupBox>
 

Rubberduck.Core/UI/Refactorings/ExtractInterface/ExtractInterfaceViewModel.cs

@@ -10,6 +10,12 @@
 
 namespace Rubberduck.UI.Refactorings
 {
+    public enum ClassInstancing
+    {
+        Private = 0,
+        PublicNotCreatable,
+    }
+
     public class ExtractInterfaceViewModel : RefactoringViewModelBase<ExtractInterfaceModel>
     {
         public ExtractInterfaceViewModel(ExtractInterfaceModel model) : base(model)
@@ -61,7 +67,7 @@ public bool IsValidInterfaceName
             }
         }
 
-        public bool IsInterfacePublicNotCreateable
+        public bool IsInterfacePublicNotCreateableEnabled
         {
             get
             {
@@ -76,6 +82,23 @@ public bool IsInterfacePublicNotCreateable
             }
         }
 
+        private ClassInstancing classInstancing = ClassInstancing.Private;
+        public ClassInstancing ClassInstancing
+        {
+            get => classInstancing;
+            set
+            {
+                if (value == classInstancing)
+                {
+                    return;
+                }
+
+                classInstancing = value;
+                OnPropertyChanged();
+            }
+        }
+
+
         private void ToggleSelection(bool value)
         {
             foreach (var item in Members)