Extend BindableProperty source gen to handle partial property initializers

src/CommunityToolkit.Maui.Core/Primitives/Defaults/AvatarViewDefaults.shared.cs

@@ -6,23 +6,23 @@ namespace CommunityToolkit.Maui.Core;
 static class AvatarViewDefaults
 {
 	/// <summary>Default avatar border width.</summary>
-	public const double DefaultBorderWidth = 1;
+	public const double BorderWidth = 1;
 
 	/// <summary>Default height request.</summary>
-	public const double DefaultHeightRequest = 48;
+	public const double HeightRequest = 48;
 
 	/// <summary>Default avatar text.</summary>
-	public const string DefaultText = "?";
+	public const string Text = "?";
 
 	/// <summary>Default width request.</summary>
-	public const double DefaultWidthRequest = 48;
+	public const double WidthRequest = 48;
 
 	/// <summary>default avatar border colour.</summary>
-	public static Color DefaultBorderColor { get; } = Colors.White;
+	public static Color BorderColor { get; } = Colors.White;
 
 	/// <summary>Default corner radius.</summary>
-	public static CornerRadius DefaultCornerRadius { get; } = new(24, 24, 24, 24);
+	public static CornerRadius CornerRadius { get; } = new(24, 24, 24, 24);
 
 	/// <summary>Default padding.</summary>
-	public static Thickness DefaultPadding { get; } = new(1);
+	public static Thickness Padding { get; } = new(1);
 }

src/CommunityToolkit.Maui.SourceGenerators.Internal.UnitTests/BindablePropertyAttributeSourceGeneratorTests/CommonUsageTests.cs

@@ -652,4 +652,77 @@ public partial class {{defaultTestClassName}}
 
 		await VerifySourceGeneratorAsync(source, expectedGenerated);
 	}
+
+
+	[Fact]
+	public async Task GenerateBindableProperty_WithInitializer_GeneratesCorrectCode()
+	{
+		const string source =
+			/* language=C#-test */
+			//lang=csharp
+			$$"""
+			using CommunityToolkit.Maui;
+			using Microsoft.Maui.Controls;
+			using System;
+
+			namespace {{defaultTestNamespace}};
+
+			public partial class {{defaultTestClassName}} : View
+			{
+			    [BindablePropertyAttribute]
+			    public partial string Text { get; set; } = "Initial Value";
+
+			    [BindablePropertyAttribute]
+			    public partial TimeSpan CustomDuration { get; set; } = TimeSpan.FromSeconds(30);
+			}
+			""";
+
+		const string expectedGenerated =
+			/* language=C#-test */
+			//lang=csharp
+			$$"""
+			// <auto-generated>
+			// See: CommunityToolkit.Maui.SourceGenerators.Internal.BindablePropertyAttributeSourceGenerator
+			#pragma warning disable
+			#nullable enable
+			namespace {{defaultTestNamespace}};
+			public partial class {{defaultTestClassName}}
+			{
+			    /// <summary>
+			    /// Backing BindableProperty for the <see cref = "Text"/> property.
+			    /// </summary>
+			    public static readonly global::Microsoft.Maui.Controls.BindableProperty TextProperty = global::Microsoft.Maui.Controls.BindableProperty.Create("Text", typeof(string), typeof({{defaultTestNamespace}}.{{defaultTestClassName}}), null, Microsoft.Maui.Controls.BindingMode.OneWay, null, null, null, null, __{{defaultTestClassName}}BindablePropertyInitHelpers.CreateDefaultText);
+			    public partial string Text { get => __{{defaultTestClassName}}BindablePropertyInitHelpers.IsInitializingText ? field : (string)GetValue(TextProperty); set => SetValue(TextProperty, value); }
+
+			    /// <summary>
+			    /// Backing BindableProperty for the <see cref = "CustomDuration"/> property.
+			    /// </summary>
+			    public static readonly global::Microsoft.Maui.Controls.BindableProperty CustomDurationProperty = global::Microsoft.Maui.Controls.BindableProperty.Create("CustomDuration", typeof(System.TimeSpan), typeof({{defaultTestNamespace}}.{{defaultTestClassName}}), null, Microsoft.Maui.Controls.BindingMode.OneWay, null, null, null, null, __{{defaultTestClassName}}BindablePropertyInitHelpers.CreateDefaultCustomDuration);
+			    public partial System.TimeSpan CustomDuration { get => __{{defaultTestClassName}}BindablePropertyInitHelpers.IsInitializingCustomDuration ? field : (System.TimeSpan)GetValue(CustomDurationProperty); set => SetValue(CustomDurationProperty, value); }
+			}
+
+			file static class __{{defaultTestClassName}}BindablePropertyInitHelpers
+			{
+			    public static bool IsInitializingText = false;
+			    public static object CreateDefaultText(global::Microsoft.Maui.Controls.BindableObject bindable)
+			    {
+			        IsInitializingText = true;
+			        var defaultValue = ((TestView)bindable).Text;
+			        IsInitializingText = false;
+			        return defaultValue;
+			    }
+
+			    public static bool IsInitializingCustomDuration = false;
+			    public static object CreateDefaultCustomDuration(global::Microsoft.Maui.Controls.BindableObject bindable)
+			    {
+			        IsInitializingCustomDuration = true;
+			        var defaultValue = ((TestView)bindable).CustomDuration;
+			        IsInitializingCustomDuration = false;
+			        return defaultValue;
+			    }
+			}
+			""";
+
+		await VerifySourceGeneratorAsync(source, expectedGenerated);
+	}
 }

src/CommunityToolkit.Maui.SourceGenerators.Internal.UnitTests/BindablePropertyAttributeSourceGeneratorTests/EdgeCaseTests.cs

@@ -456,4 +456,51 @@ public partial class {{defaultTestClassName}}
 
 		await VerifySourceGeneratorAsync(source, expectedGenerated);
 	}
+
+	[Fact]
+	public async Task GenerateBindableProperty_WithBothInitializerAndDefault_GeneratedCodeDefaultsToUseDefaultValueCreatorMethod()
+	{
+		const string source =
+			/* language=C#-test */
+			//lang=csharp
+			$$"""
+			using CommunityToolkit.Maui;
+			using Microsoft.Maui.Controls;
+			using System;
+
+			namespace {{defaultTestNamespace}};
+
+			public partial class {{defaultTestClassName}} : View
+			{
+			    [BindablePropertyAttribute(DefaultValueCreatorMethodName = nameof(CreateDefaultText))]
+			    public partial string Text { get; set; } = "Initial Value";
+
+				static string CreateDefaultText(BindableObject bindable)
+				{
+					return "Initial Value";
+				}
+			}
+			""";
+
+		const string expectedGenerated =
+			/* language=C#-test */
+			//lang=csharp
+			$$"""
+			// <auto-generated>
+			// See: CommunityToolkit.Maui.SourceGenerators.Internal.BindablePropertyAttributeSourceGenerator
+			#pragma warning disable
+			#nullable enable
+			namespace {{defaultTestNamespace}};
+			public partial class {{defaultTestClassName}}
+			{
+			    /// <summary>
+			    /// Backing BindableProperty for the <see cref = "Text"/> property.
+			    /// </summary>
+			    public static readonly global::Microsoft.Maui.Controls.BindableProperty TextProperty = global::Microsoft.Maui.Controls.BindableProperty.Create("Text", typeof(string), typeof({{defaultTestNamespace}}.{{defaultTestClassName}}), null, Microsoft.Maui.Controls.BindingMode.OneWay, null, null, null, null, CreateDefaultText);
+			    public partial string Text { get => false ? field : (string)GetValue(TextProperty); set => SetValue(TextProperty, value); }
+			}
+			""";
+
+		await VerifySourceGeneratorAsync(source, expectedGenerated);
+	}
 }

src/CommunityToolkit.Maui.SourceGenerators.Internal.UnitTests/BindablePropertyModelTests.cs

@@ -29,7 +29,8 @@ public void BindablePropertyName_ReturnsCorrectPropertyName()
 			"null",
 			string.Empty,
 			true, // IsReadOnlyBindableProperty
-			string.Empty // SetterAccessibility
+			string.Empty, // SetterAccessibility
+			false
 		);
 
 		// Act
@@ -56,6 +57,7 @@ public void BindablePropertyModel_WithAllParameters_StoresCorrectValues()
 		const string coerceValueMethodName = "CoerceValue";
 		const string defaultValueCreatorMethodName = "CreateDefaultValue";
 		const string newKeywordText = "new ";
+		const bool hasInitializer = false;
 
 		// Act
 		var model = new BindablePropertyModel(
@@ -71,7 +73,8 @@ public void BindablePropertyModel_WithAllParameters_StoresCorrectValues()
 			defaultValueCreatorMethodName,
 			newKeywordText,
 			true, // IsReadOnlyBindableProperty
-			string.Empty // SetterAccessibility
+			string.Empty, // SetterAccessibility
+			hasInitializer
 		);
 
 		// Assert
@@ -86,7 +89,10 @@ public void BindablePropertyModel_WithAllParameters_StoresCorrectValues()
 		Assert.Equal(coerceValueMethodName, model.CoerceValueMethodName);
 		Assert.Equal(defaultValueCreatorMethodName, model.DefaultValueCreatorMethodName);
 		Assert.Equal(newKeywordText, model.NewKeywordText);
+		Assert.Equal(hasInitializer, model.HasInitializer);
 		Assert.Equal("TestPropertyProperty", model.BindablePropertyName);
+		Assert.Equal(defaultValueCreatorMethodName, model.EffectiveDefaultValueCreatorMethodName);
+		Assert.Equal("IsInitializingTestProperty", model.InitializingPropertyName);
 	}
 
 	[Fact]
@@ -128,7 +134,8 @@ public void SemanticValues_WithClassInfoAndProperties_StoresCorrectValues()
 			"null",
 			string.Empty,
 			true, // IsReadOnlyBindableProperty
-			string.Empty // SetterAccessibilityText
+			string.Empty, // SetterAccessibilityText
+			false
 		);
 
 		var bindableProperties = new[] { bindableProperty }.ToImmutableArray();
@@ -156,4 +163,80 @@ static Compilation CreateCompilation(string source)
 			references,
 			new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));
 	}
+
+	[Fact]
+	public void BindablePropertyName_WithInitializer_ReturnsCorrectEffectiveDefaultValueCreatorMethodName()
+	{
+		// Arrange
+		var compilation = CreateCompilation(
+			"""
+			public class TestClass { public string TestProperty { get; set; } = "Initial Value"; }");
+			""");
+		var typeSymbol = compilation.GetTypeByMetadataName("TestClass")!;
+		var propertySymbol = typeSymbol.GetMembers("TestProperty").OfType<IPropertySymbol>().First();
+
+		const string propertyName = "TestProperty";
+		const bool hasInitializer = true;
+
+		var model = new BindablePropertyModel(
+			propertyName,
+			propertySymbol.Type,
+			typeSymbol,
+			"null",
+			"Microsoft.Maui.Controls.BindingMode.OneWay",
+			"null",
+			"null",
+			"null",
+			"null",
+			"null",
+			string.Empty,
+			true,
+			string.Empty,
+			hasInitializer
+		);
+
+		// Act
+		var effectiveDefaultValueCreatorMethodName = model.EffectiveDefaultValueCreatorMethodName;
+
+		// Assert
+		Assert.Equal("CreateDefault" + propertyName, effectiveDefaultValueCreatorMethodName);
+	}
+
+	[Fact]
+	public void BindablePropertyName_WithInitializerAndDefaulValueCreator_ReturnsCorrectEffectiveDefaultValueCreatorMethodName()
+	{
+		// Arrange
+		var compilation = CreateCompilation(
+			"""
+			public class TestClass { public string TestProperty { get; set; } = "Initial Value"; }
+			""");
+		var typeSymbol = compilation.GetTypeByMetadataName("TestClass")!;
+		var propertySymbol = typeSymbol.GetMembers("TestProperty").OfType<IPropertySymbol>().First();
+
+		const string propertyName = "TestProperty";
+		const bool hasInitializer = true;
+
+		var model = new BindablePropertyModel(
+			propertyName,
+			propertySymbol.Type,
+			typeSymbol,
+			"null",
+			"Microsoft.Maui.Controls.BindingMode.OneWay",
+			"null",
+			"null",
+			"null",
+			"null",
+			"CreateTextDefaultValue",
+			string.Empty,
+			true,
+			string.Empty,
+			hasInitializer
+		);
+
+		// Act
+		var effectiveDefaultValueCreatorMethodName = model.EffectiveDefaultValueCreatorMethodName;
+
+		// Assert
+		Assert.Equal("CreateTextDefaultValue", effectiveDefaultValueCreatorMethodName);
+	}
 }