Feature OAPH From Observable Property (#32)

* Feature OAPH From Observable Property

A ReadOnly Property will be generated, a OAPH Helper will be generated, the Read Only Property will be attached to the Observable upon calling InitializeOAPH()
If PropertyName is not set the Method Name is added to "Property" to make MethodNameProperty, otherwise the PropertyName property of the Attribute will be used as the base for generated elements.

* Update Documentation

Author: ChrisPulman

README.md

@@ -1,11 +1,10 @@
 # ReactiveUI.SourceGenerators
-Use source generators to generate ReactiveUI objects. 
-
-Not taking public contributions at this time
+Use source generators to generate ReactiveUI objects.
 
 These Source Generators were designed to work in full with ReactiveUI V19.5.31 and newer supporting all features, currently:
 - [Reactive]
 - [ObservableAsProperty]
+- [ObservableAsProperty(PropertyName = "ReadOnlyPropertyName")]
 - [ReactiveCommand]
 - [ReactiveCommand(CanExecute = nameof(IObservableBoolName))] with CanExecute
 - [ReactiveCommand][property: AttribueToAddToCommand] with Attribute passthrough
@@ -75,6 +74,8 @@ public partial class MyReactiveClass : ReactiveObject
 ```
 
 ## Usage ObservableAsPropertyHelper `[ObservableAsProperty]`
+
+### Usage ObservableAsPropertyHelper with Field
 ```csharp
 using ReactiveUI.SourceGenerators;
 
@@ -93,6 +94,80 @@ public partial class MyReactiveClass : ReactiveObject
 }
 ```
 
+### Usage ObservableAsPropertyHelper with Observable Property
+```csharp
+using ReactiveUI.SourceGenerators;
+
+public partial class MyReactiveClass : ReactiveObject
+{    
+    public MyReactiveClass()
+    { 
+        // Initialize generated _myObservablePropertyHelper
+        // for the generated MyObservableProperty
+        InitializeOAPH();
+    }
+
+    [ObservableAsProperty]
+    IObservable<string> MyObservable => Observable.Return("Test Value");
+}
+```
+
+### Usage ObservableAsPropertyHelper with Observable Property and specific PropertyName
+```csharp
+using ReactiveUI.SourceGenerators;
+
+public partial class MyReactiveClass : ReactiveObject
+{    
+    public MyReactiveClass()
+    { 
+        // Initialize generated _testValuePropertyHelper
+        // for the generated TestValueProperty
+        InitializeOAPH();
+    }
+
+    [ObservableAsProperty(PropertyName = TestValueProperty)]
+    IObservable<string> MyObservable => Observable.Return("Test Value");
+}
+```
+
+### Usage ObservableAsPropertyHelper with Observable Method
+
+NOTE: This does not support methods with parameters
+```csharp
+using ReactiveUI.SourceGenerators;
+
+public partial class MyReactiveClass : ReactiveObject
+{    
+    public MyReactiveClass()
+    { 
+        // Initialize generated _myObservablePropertyHelper
+        // for the generated MyObservableProperty
+        InitializeOAPH();
+    }
+
+    [ObservableAsProperty]
+    IObservable<string> MyObservable() => Observable.Return("Test Value");
+}
+```
+
+### Usage ObservableAsPropertyHelper with Observable Method and specific PropertyName
+```csharp
+using ReactiveUI.SourceGenerators;
+
+public partial class MyReactiveClass : ReactiveObject
+{    
+    public MyReactiveClass()
+    { 
+        // Initialize generated _testValuePropertyHelper
+        // for the generated TestValueProperty
+        InitializeOAPH();
+    }
+
+    [ObservableAsProperty(PropertyName = TestValueProperty)]
+    IObservable<string> MyObservable() => Observable.Return("Test Value");
+}
+```
+
 ## Usage ReactiveCommand `[ReactiveCommand]`
 
 ### Usage ReactiveCommand without parameter
@@ -279,7 +354,7 @@ The class must inherit from a UI Control from any of the following platforms and
 ```csharp
 using ReactiveUI.SourceGenerators;
 
-[IViewFor(MyReactiveClass)]
+[IViewFor(nameof(MyReactiveClass))]
 public partial class MyReactiveControl : UserControl
 {
     public MyReactiveControl()
@@ -291,4 +366,4 @@ public partial class MyReactiveControl : UserControl
 ```
 
 ### TODO:
-- Add ObservableAsProperty to generate from a IObservable creating a property and the property helper wired to the Observable.
+- Add ObservableAsProperty to generate from a IObservable method with parameters.

src/ReactiveUI.SourceGenerators.Execute/TestViewModel.cs

@@ -60,7 +60,8 @@ public TestViewModel()
         Test8ObservableCommand?.Execute(100).Subscribe(Console.Out.WriteLine);
         Console.Out.WriteLine($"Test2Property Value: {Test2Property}");
         Console.Out.WriteLine($"Test2Property underlying Value: {_test2Property}");
-
+        Console.Out.WriteLine(ObservableAsPropertyTest2Property);
+        Console.Out.WriteLine(MyReadOnlyProperty);
         Test9AsyncCommand?.ThrownExceptions.Subscribe(Console.Out.WriteLine);
         var cancel = Test9AsyncCommand?.Execute().Subscribe();
         Task.Delay(1000).Wait();
@@ -94,9 +95,16 @@ public TestViewModel()
     /// <value>
     /// The can execute test1.
     /// </value>
-#pragma warning disable CA1822 // Mark members as static
-    public IObservable<bool> CanExecuteTest1 => Observable.Return(true);
-#pragma warning restore CA1822 // Mark members as static
+    public IObservable<bool> CanExecuteTest1 => ObservableAsPropertyTest2.Select(x => x > 0);
+
+    /// <summary>
+    /// Gets the observable as property test2.
+    /// </summary>
+    /// <value>
+    /// The observable as property test2.
+    /// </value>
+    [ObservableAsProperty]
+    public IObservable<int> ObservableAsPropertyTest2 => Observable.Return(9);
 
     /// <summary>
     /// Gets observables as property test.
@@ -113,7 +121,7 @@ public TestViewModel()
     [ReactiveCommand(CanExecute = nameof(CanExecuteTest1))]
     [property: JsonInclude]
     [property: Test(AParameter = "Test Input")]
-    private void Test1() => Console.Out.WriteLine("Test1");
+    private void Test1() => Console.Out.WriteLine("Test1 Command Executed");
 
     /// <summary>
     /// Test3s the asynchronous.

src/ReactiveUI.SourceGenerators/Diagnostics/SuppressionDescriptors.cs

@@ -22,7 +22,7 @@ internal static class SuppressionDescriptors
     public static readonly SuppressionDescriptor ReactiveCommandDoesNotAccessInstanceData = new(
         id: "RXUISPR0003",
         suppressedDiagnosticId: "CA1822",
-        justification: "Methods using [ReactiveCommand] do not need to be static");
+        justification: "Methods using [ReactiveCommand] or [ObservableAsProperty] do not need to be static");
 
     public static readonly SuppressionDescriptor ReactiveFieldsShouldNotBeReadOnly = new(
         id: "RXUISPR0004",

src/ReactiveUI.SourceGenerators/Diagnostics/Suppressions/OAPHMethodDoesNotNeedToBeStaticDiagnosticSuppressor.cs

@@ -9,6 +9,7 @@
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Diagnostics;
 using ReactiveUI.SourceGenerators.Extensions;
+using ReactiveUI.SourceGenerators.Helpers;
 using static ReactiveUI.SourceGenerators.Diagnostics.SuppressionDescriptors;
 
 namespace ReactiveUI.SourceGenerators.Diagnostics.Suppressions;
@@ -40,12 +41,29 @@ public override void ReportSuppressions(SuppressionAnalysisContext context)
 
                 // Check if the method is using [ObservableAsProperty], in which case we should suppress the warning
                 if (declaredSymbol is IMethodSymbol methodSymbol &&
-                    semanticModel.Compilation.GetTypeByMetadataName("ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute") is INamedTypeSymbol oaphSymbol &&
+                    semanticModel.Compilation.GetTypeByMetadataName(AttributeDefinitions.ObservableAsPropertyAttributeType) is INamedTypeSymbol oaphSymbol &&
                     methodSymbol.HasAttributeWithType(oaphSymbol))
                 {
                     context.ReportSuppression(Suppression.Create(ReactiveCommandDoesNotAccessInstanceData, diagnostic));
                 }
             }
+
+            // Check that the target is a property declaration, which is the case we're looking for
+            if (syntaxNode is PropertyDeclarationSyntax propertyDeclaration)
+            {
+                var semanticModel = context.GetSemanticModel(syntaxNode.SyntaxTree);
+
+                // Get the method symbol from the first variable declaration
+                ISymbol? declaredSymbol = semanticModel.GetDeclaredSymbol(propertyDeclaration, context.CancellationToken);
+
+                // Check if the method is using [ObservableAsProperty], in which case we should suppress the warning
+                if (declaredSymbol is IPropertySymbol propertySymbol &&
+                    semanticModel.Compilation.GetTypeByMetadataName(AttributeDefinitions.ObservableAsPropertyAttributeType) is INamedTypeSymbol oaphSymbol &&
+                    propertySymbol.HasAttributeWithType(oaphSymbol))
+                {
+                    context.ReportSuppression(Suppression.Create(ReactiveCommandDoesNotAccessInstanceData, diagnostic));
+                }
+            }
         }
     }
 }

src/ReactiveUI.SourceGenerators/Diagnostics/Suppressions/ObservableAsPropertyAttributeWithFieldNeverReadDiagnosticSuppressor.cs

@@ -9,6 +9,7 @@
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Diagnostics;
 using ReactiveUI.SourceGenerators.Extensions;
+using ReactiveUI.SourceGenerators.Helpers;
 using static ReactiveUI.SourceGenerators.Diagnostics.SuppressionDescriptors;
 
 namespace ReactiveUI.SourceGenerators.Diagnostics.Suppressions
@@ -40,7 +41,7 @@ public override void ReportSuppressions(SuppressionAnalysisContext context)
 
                     // Check if the method is using [ObservableAsProperty], in which case we should suppress the warning
                     if (declaredSymbol is IMethodSymbol methodSymbol &&
-                        semanticModel.Compilation.GetTypeByMetadataName("ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute") is INamedTypeSymbol reactiveCommandSymbol &&
+                        semanticModel.Compilation.GetTypeByMetadataName(AttributeDefinitions.ObservableAsPropertyAttributeType) is INamedTypeSymbol reactiveCommandSymbol &&
                         methodSymbol.HasAttributeWithType(reactiveCommandSymbol))
                     {
                         context.ReportSuppression(Suppression.Create(FieldIsUsedToGenerateAObservableAsPropertyHelper, diagnostic));

src/ReactiveUI.SourceGenerators/Diagnostics/Suppressions/ReactiveCommandAttributeWithFieldOrPropertyTargetDiagnosticSuppressor.cs

@@ -9,6 +9,7 @@
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Diagnostics;
 using ReactiveUI.SourceGenerators.Extensions;
+using ReactiveUI.SourceGenerators.Helpers;
 using static ReactiveUI.SourceGenerators.Diagnostics.SuppressionDescriptors;
 
 namespace ReactiveUI.SourceGenerators.Diagnostics.Suppressions
@@ -40,7 +41,7 @@ public override void ReportSuppressions(SuppressionAnalysisContext context)
 
                     // Check if the method is using [ReactiveCommand], in which case we should suppress the warning
                     if (declaredSymbol is IMethodSymbol methodSymbol &&
-                        semanticModel.Compilation.GetTypeByMetadataName("ReactiveUI.SourceGenerators.ReactiveCommandAttribute") is INamedTypeSymbol reactiveCommandSymbol &&
+                        semanticModel.Compilation.GetTypeByMetadataName(AttributeDefinitions.ReactiveCommandAttributeType) is INamedTypeSymbol reactiveCommandSymbol &&
                         methodSymbol.HasAttributeWithType(reactiveCommandSymbol))
                     {
                         context.ReportSuppression(Suppression.Create(FieldOrPropertyAttributeListForReactiveCommandMethod, diagnostic));

src/ReactiveUI.SourceGenerators/Diagnostics/Suppressions/ReactiveCommandMethodDoesNotNeedToBeStaticDiagnosticSuppressor.cs

@@ -9,6 +9,7 @@
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Diagnostics;
 using ReactiveUI.SourceGenerators.Extensions;
+using ReactiveUI.SourceGenerators.Helpers;
 using static ReactiveUI.SourceGenerators.Diagnostics.SuppressionDescriptors;
 
 namespace ReactiveUI.SourceGenerators.Diagnostics.Suppressions;
@@ -40,7 +41,7 @@ public override void ReportSuppressions(SuppressionAnalysisContext context)
 
                 // Check if the method is using [ReactiveCommand], in which case we should suppress the warning
                 if (declaredSymbol is IMethodSymbol methodSymbol &&
-                    semanticModel.Compilation.GetTypeByMetadataName("ReactiveUI.SourceGenerators.ReactiveCommandAttribute") is INamedTypeSymbol reactiveCommandSymbol &&
+                    semanticModel.Compilation.GetTypeByMetadataName(AttributeDefinitions.ReactiveCommandAttributeType) is INamedTypeSymbol reactiveCommandSymbol &&
                     methodSymbol.HasAttributeWithType(reactiveCommandSymbol))
                 {
                     context.ReportSuppression(Suppression.Create(ReactiveCommandDoesNotAccessInstanceData, diagnostic));

src/ReactiveUI.SourceGenerators/Diagnostics/Suppressions/ReactiveFieldDoesNotNeedToBeReadOnlyDiagnosticSuppressor.cs

@@ -9,6 +9,7 @@
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Diagnostics;
 using ReactiveUI.SourceGenerators.Extensions;
+using ReactiveUI.SourceGenerators.Helpers;
 using static ReactiveUI.SourceGenerators.Diagnostics.SuppressionDescriptors;
 
 namespace ReactiveUI.SourceGenerators.Diagnostics.Suppressions
@@ -40,7 +41,7 @@ public override void ReportSuppressions(SuppressionAnalysisContext context)
 
                     // Check if the method is using [Reactive], in which case we should suppress the warning
                     if (declaredSymbol is IFieldSymbol fieldSymbol &&
-                        semanticModel.Compilation.GetTypeByMetadataName("ReactiveUI.SourceGenerators.ReactiveAttribute") is INamedTypeSymbol reactiveSymbol &&
+                        semanticModel.Compilation.GetTypeByMetadataName(AttributeDefinitions.ReactiveAttributeType) is INamedTypeSymbol reactiveSymbol &&
                         fieldSymbol.HasAttributeWithType(reactiveSymbol))
                     {
                         context.ReportSuppression(Suppression.Create(ReactiveFieldsShouldNotBeReadOnly, diagnostic));

src/ReactiveUI.SourceGenerators/Helpers/AttributeDefinitions.cs

@@ -9,6 +9,8 @@ namespace ReactiveUI.SourceGenerators.Helpers;
 
 internal static class AttributeDefinitions
 {
+    public const string GeneratedCode = "global::System.CodeDom.Compiler.GeneratedCode";
+    public const string ExcludeFromCodeCoverage = "global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage";
     public const string ReactiveObjectAttribute = """
 // Copyright (c) 2024 .NET Foundation and Contributors. All rights reserved.
 // Licensed to the .NET Foundation under one or more agreements.
@@ -33,6 +35,7 @@ public sealed class ReactiveObjectAttribute : Attribute;
 #pragma warning restore
 """;
 
+    public const string ReactiveCommandAttributeType = "ReactiveUI.SourceGenerators.ReactiveCommandAttribute";
     public const string ReactiveCommandAttribute = """
 // Copyright (c) 2024 .NET Foundation and Contributors. All rights reserved.
 // Licensed to the .NET Foundation under one or more agreements.
@@ -66,6 +69,7 @@ public sealed class ReactiveCommandAttribute : Attribute
 #pragma warning restore
 """;
 
+    public const string ReactiveAttributeType = "ReactiveUI.SourceGenerators.ReactiveAttribute";
     public const string ReactiveAttribute = """
 // Copyright (c) 2024 .NET Foundation and Contributors. All rights reserved.
 // Licensed to the .NET Foundation under one or more agreements.
@@ -90,6 +94,7 @@ public sealed class ReactiveAttribute : Attribute;
 #pragma warning restore
 """;
 
+    public const string ObservableAsPropertyAttributeType = "ReactiveUI.SourceGenerators.ObservableAsPropertyAttribute";
     public const string ObservableAsPropertyAttribute = """
 // Copyright (c) 2024 .NET Foundation and Contributors. All rights reserved.
 // Licensed to the .NET Foundation under one or more agreements.
@@ -104,11 +109,11 @@ public sealed class ReactiveAttribute : Attribute;
 namespace ReactiveUI.SourceGenerators;
 
 /// <summary>
-/// ReactivePropertyAttribute.
+/// ObservableAsPropertyAttribute.
 /// </summary>
 /// <seealso cref="Attribute" />
 [global::System.CodeDom.Compiler.GeneratedCode("ReactiveUI.SourceGenerators.ObservableAsPropertyGenerator", "1.1.0.0")]
-[AttributeUsage(AttributeTargets.Field | AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
+[AttributeUsage(AttributeTargets.Field | AttributeTargets.Property | AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
 public sealed class ObservableAsPropertyAttribute : Attribute
 {
     /// <summary>
@@ -123,6 +128,7 @@ public sealed class ObservableAsPropertyAttribute : Attribute
 #pragma warning restore
 """;
 
+    public const string IViewForAttributeType = "ReactiveUI.SourceGenerators.IViewForAttribute";
     public const string IViewForAttribute = """
 // Copyright (c) 2024 .NET Foundation and Contributors. All rights reserved.
 // Licensed to the .NET Foundation under one or more agreements.
@@ -137,7 +143,7 @@ public sealed class ObservableAsPropertyAttribute : Attribute
 namespace ReactiveUI.SourceGenerators;
 
 /// <summary>
-/// ReactiveObjectAttribute.
+/// IViewForAttribute.
 /// </summary>
 /// <seealso cref="System.Attribute" />
 /// <remarks>

src/ReactiveUI.SourceGenerators/IViewFor/IViewForGenerator.cs

@@ -17,7 +17,6 @@
 using ReactiveUI.SourceGenerators.Helpers;
 using ReactiveUI.SourceGenerators.Input.Models;
 using ReactiveUI.SourceGenerators.Models;
-using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
 
 namespace ReactiveUI.SourceGenerators;
 
@@ -28,19 +27,18 @@ namespace ReactiveUI.SourceGenerators;
 public sealed partial class IViewForGenerator : IIncrementalGenerator
 {
     private const string GeneratedCode = "global::System.CodeDom.Compiler.GeneratedCode";
-    private const string IViewForAttribute = "ReactiveUI.SourceGenerators.IViewForAttribute";
 
     /// <inheritdoc/>
     public void Initialize(IncrementalGeneratorInitializationContext context)
     {
         context.RegisterPostInitializationOutput(ctx =>
-            ctx.AddSource($"{IViewForAttribute}.g.cs", SourceText.From(AttributeDefinitions.IViewForAttribute, Encoding.UTF8)));
+            ctx.AddSource($"{AttributeDefinitions.IViewForAttributeType}.g.cs", SourceText.From(AttributeDefinitions.IViewForAttribute, Encoding.UTF8)));
 
         // Gather info for all annotated IViewFor Classes
         IncrementalValuesProvider<(HierarchyInfo Hierarchy, Result<IViewForInfo> Info)> iViewForInfoWithErrors =
             context.SyntaxProvider
             .ForAttributeWithMetadataName(
-                IViewForAttribute,
+                AttributeDefinitions.IViewForAttributeType,
                 static (node, _) => node is ClassDeclarationSyntax { AttributeLists.Count: > 0 },
                 static (context, token) =>
                 {
@@ -55,7 +53,7 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
                         var compilation = context.SemanticModel.Compilation;
                         var semanticModel = compilation.GetSemanticModel(context.SemanticModel.SyntaxTree);
                         var symbol = ModelExtensions.GetDeclaredSymbol(semanticModel, declaredClass, token)!;
-                        if (symbol.TryGetAttributeWithFullyQualifiedMetadataName(IViewForAttribute, out var attributeData))
+                        if (symbol.TryGetAttributeWithFullyQualifiedMetadataName(AttributeDefinitions.IViewForAttributeType, out var attributeData))
                         {
                             token.ThrowIfCancellationRequested();
                             var classSymbol = symbol as INamedTypeSymbol;