Reduce the use of string builder

Author: ChrisPulman

README.md

@@ -567,6 +567,8 @@ public partial class MyReactiveControl : UserControl
 
 this will generate the following code to enable you register the marked Views as `IViewFor<ViewModel>` with Splat:
 ```csharp
+using ReactiveUI.SourceGenerators;
+
 Splat.Locator.CurrentMutable.RegisterViewsForViewModelsSourceGenerated();
 ```
 

src/ReactiveUI.SourceGenerators.Execute/Program.cs

@@ -3,7 +3,7 @@
 // The ReactiveUI and contributors licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for full license information.
 
-using ReactiveUI;
+using ReactiveUI.SourceGenerators;
 using Splat;
 
 namespace SGReactiveUI.SourceGenerators.Test;

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

@@ -323,27 +323,7 @@ private static string GenerateRegistrationExtensions(in ImmutableArray<IViewForI
             .ToImmutableArray();
 
         var sb = new StringBuilder();
-        sb
-            .AppendLine("// <auto-generated/>")
-            .AppendLine("#pragma warning disable")
-            .AppendLine("#nullable enable")
-            .AppendLine()
-            .AppendLine("using global::ReactiveUI;")
-            .AppendLine("using global::Splat;")
-            .AppendLine()
-            .AppendLine("namespace ReactiveUI")
-            .AppendLine("{")
-            .AppendLine("    /// <summary>")
-            .AppendLine("    /// Source-generated registration extensions for ReactiveUI views.")
-            .AppendLine("    /// </summary>")
-            .AppendLine("    internal static class ReactiveUISourceGeneratorsExtensions")
-            .AppendLine("    {")
-            .AppendLine($"        [{AttributeDefinitions.GeneratedCode}(\"{GeneratorName}\", \"{GeneratorVersion}\")] ")
-            .AppendLine("        public static void RegisterViewsForViewModelsSourceGenerated(this global::Splat.IMutableDependencyResolver resolver)")
-            .AppendLine("        {")
-            .AppendLine("            if (resolver is null) throw new global::System.ArgumentNullException(nameof(resolver));")
-            .AppendLine();
-
+        sb.AppendLine("if (resolver is null) throw new global::System.ArgumentNullException(nameof(resolver));");
         foreach (var item in registrations)
         {
             var vmType = item.ViewModelTypeName;
@@ -370,13 +350,32 @@ private static string GenerateRegistrationExtensions(in ImmutableArray<IViewForI
             }
         }
 
-        sb
-            .AppendLine("        }")
-            .AppendLine("    }")
-            .AppendLine("}")
-            .AppendLine("#nullable restore")
-            .AppendLine("#pragma warning restore");
+        var registrationsBody = sb.ToString().TrimEnd();
+        return
+        $$"""
+// <auto-generated/>
+#pragma warning disable
+#nullable enable
+
+using global::ReactiveUI;
+using global::Splat;
 
-        return sb.ToString();
+namespace ReactiveUI.SourceGenerators
+{
+    /// <summary>
+    /// Source-generated registration extensions for ReactiveUI views.
+    /// </summary>
+    internal static class ReactiveUISourceGeneratorsExtensions
+    {
+        [global::System.CodeDom.Compiler.GeneratedCode("{{GeneratorName}}", "{{GeneratorVersion}}")]
+        public static void RegisterViewsForViewModelsSourceGenerated(this global::Splat.IMutableDependencyResolver resolver)
+        {
+            {{registrationsBody}}
+        }
+    }
+}
+#nullable restore
+#pragma warning restore
+""";
     }
 }