FIx For IViewFor with Generic Class (#118)

Author: ChrisPulman

README.md

@@ -389,6 +389,23 @@ The class must inherit from a UI Control from any of the following platforms and
 - Avalonia (Avalonia)
 - Uno (Windows.UI.Xaml).
 
+### Usage IViewFor with ViewModel Name - Generic Types should be used with the fully qualified name, otherwise use nameof(ViewModelTypeName)
+```csharp
+using ReactiveUI.SourceGenerators;
+
+[IViewFor("MyReactiveGenericClass<int>")]
+public partial class MyReactiveControl : UserControl
+{
+    public MyReactiveControl()
+    {
+        InitializeComponent();
+        MyReactiveClass = new MyReactiveClass();
+    }
+}
+```
+
+### Usage IViewFor with ViewModel Type
+
 ```csharp
 using ReactiveUI.SourceGenerators;
 

src/ReactiveUI.SourceGenerators/AttributeDefinitions.cs

@@ -207,6 +207,18 @@ namespace ReactiveUI.SourceGenerators;
 [global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.IViewForGenerator", "1.1.0.0")]
 [AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = false)]
 internal sealed class IViewForAttribute<T> : Attribute;
+
+/// <summary>
+/// IViewForAttribute.
+/// </summary>
+/// <seealso cref="System.Attribute" />
+/// <remarks>
+/// Initializes a new instance of the <see cref="IViewForAttribute"/> class.
+/// </remarks>
+/// <param name="viewModelType">Type of the view model.</param>
+[global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.IViewForGenerator", "1.1.0.0")]
+[AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = false)]
+internal sealed class IViewForAttribute(string? viewModelType) : Attribute;
 #nullable restore
 #pragma warning restore
 """;

src/ReactiveUI.SourceGenerators/IViewFor/IViewForGenerator.Execute.cs

@@ -50,9 +50,11 @@ public partial class IViewForGenerator
 
         token.ThrowIfCancellationRequested();
 
+        var constructorArgument = attributeData.GetConstructorArguments<string>().FirstOrDefault();
         var genericArgument = attributeData.GetGenericType();
         token.ThrowIfCancellationRequested();
-        if (!(genericArgument is string viewModelTypeName && viewModelTypeName.Length > 0))
+        var viewModelTypeName = string.IsNullOrWhiteSpace(constructorArgument) ? genericArgument : constructorArgument;
+        if (string.IsNullOrWhiteSpace(viewModelTypeName))
         {
             return default;
         }