Find MauiProgram namespace the app is running in

README.md

@@ -402,7 +402,8 @@ See the [IDialogService interface in the repository](https://github.com/BurkusCa
 
 ## Advanced / complexities
 The below are some things of note that may help prevent issues from arising:
-- When you inherit from `BurkusMvvmApplication`, the `MainPage` of the app will be automatically set to a `NavigationPage`. This means the first page you push can be a `ContentPage` rather than needing to push a `NavigationPage`. This may change in the future.
+- The `MainPage` of the app will be automatically set to a `NavigationPage`. This means the first page you push can be a `ContentPage` rather than needing to push a `NavigationPage`. This may change in the future.
+- A source generator will automatically add code overriding `Window CreateWindow(IActivationState? activationState)` in your `App.xaml.cs` class.
 - Adding this package to a project will automatically import the `Burkus.Mvvm.Maui` namespace globally if you have [`ImplicitUsings`](https://devblogs.microsoft.com/dotnet/welcome-to-csharp-10/#implicit-usings) enabled in your project. You can opt out of this by including the following in your `.csproj` file:
 ``` xml
 <Using Remove="Burkus.Mvvm.Maui" />

samples/DemoApp/DemoApp.csproj

@@ -47,6 +47,14 @@
     <MauiAsset Include="Resources\Raw\**" LogicalName="%(RecursiveDir)%(Filename)%(Extension)" />
   </ItemGroup>
 
+  <!-- Source generators -->
+  <!-- Uncomment to debug the output of the source generators
+  <PropertyGroup>
+    <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
+    <CompilerGeneratedFilesOutputPath>Generated</CompilerGeneratedFilesOutputPath>
+  </PropertyGroup>
+  -->
+
   <ItemGroup>
     <None Remove="Resources\Images\contacts.png" />
     <None Remove="Resources\Images\reminders.png" />

src/Burkus.Mvvm.Maui.SourceGenerators/AppSourceGenerator.cs

@@ -1,6 +1,7 @@
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.Text;
+using System;
 using System.Linq;
 using System.Text;
 
@@ -27,37 +28,51 @@ public void Execute(GeneratorExecutionContext context)
         // check if the App class is partial and inherits from Application
         var appSymbol = semanticModel.GetDeclaredSymbol(receiver.AppClass);
         if (appSymbol is null || !isPartial || !appSymbol.BaseType.Equals(semanticModel.Compilation.GetTypeByMetadataName("Microsoft.Maui.Controls.Application")))
-            return;
+        {
+            throw new Exception("You must have a partial class called \"App\" that inherits from Application in your .NET MAUI project.");
+        }
+
+        // get the MAUI program we are running in
+
+        var assembly = context.Compilation.Assembly;
+        var mauiProgramName = $"{assembly.Name}.MauiProgram";
+        var mauiProgram = context.Compilation
+            .GetTypeByMetadataName(mauiProgramName);
+
+        if (mauiProgram is null)
+        {
+            throw new Exception("You must have a class called \"MauiProgram\" in your .NET MAUI project.");
+        }
 
         // generate the source code for the CreateWindow method
-        var sourceBuilder = """
-                            // <auto-generated>
-                            //     This code was generated by a tool. Burkus.Mvvm.Maui generated this.
-                            //
-                            //     Changes to this file may cause incorrect behavior and will be lost if
-                            //     the code is regenerated.
-                            // </auto-generated>
-
-                            partial class App : Application
-                            {
-                                protected override Window CreateWindow(IActivationState? activationState)
-                                {
-                                    Current.MainPage = new NavigationPage();
-
-                                    var burkusMvvmBuilder = ServiceResolver.Resolve<IBurkusMvvmBuilder>();
-                                    var navigationService = ServiceResolver.Resolve<INavigationService>();
-                                    var serviceProvider = ServiceResolver.GetServiceProvider();
-
-                                    // perform the user's desired initialization logic
-                                    if (burkusMvvmBuilder.onStartFunc != null)
-                                    {
-                                        burkusMvvmBuilder.onStartFunc.Invoke(navigationService, serviceProvider);
-                                    }
-
-                                    return base.CreateWindow(activationState);
-                                }
-                            }
-                            """;
+        var sourceBuilder = $@"// <auto-generated>
+//     This code was generated by a tool. Burkus.Mvvm.Maui generated this.
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+
+namespace {mauiProgram.ContainingNamespace.ToDisplayString()};
+
+public partial class App : Application
+{{
+    protected override Window CreateWindow(IActivationState? activationState)
+    {{
+        Current.MainPage = new NavigationPage();
+
+        var burkusMvvmBuilder = ServiceResolver.Resolve<IBurkusMvvmBuilder>();
+        var navigationService = ServiceResolver.Resolve<INavigationService>();
+        var serviceProvider = ServiceResolver.GetServiceProvider();
+
+        // perform the user's desired initialization logic
+        if (burkusMvvmBuilder.onStartFunc != null)
+        {{
+            burkusMvvmBuilder.onStartFunc.Invoke(navigationService, serviceProvider);
+        }}
+
+        return base.CreateWindow(activationState);
+    }}
+}}";
 
         // add the generated source file to the compilation
         context.AddSource("App-BurkusMvvmApplication.g", SourceText.From(sourceBuilder.ToString(), Encoding.UTF8));