Implemented implicit types for new expressions

With C# 9.0, the `new` keyword only needs a type declaration if the type is otherwise unknown (e.g., `var`) or ambiguous (e.g., with an interface, or overloaded method). Otherwise, it can just use `new()`. This is especially useful for property initializers, which can be incredibly repetitive.

Note: This apparently cannot be done for generics (e.g., `new T()` cannot become `new()`). I'll need to look into that, but for now it's useful to know that it doesn't work.

Author: JeremyCaney

OnTopic.AspNetCore.Mvc.Tests/OnTopic.AspNetCore.Mvc.Tests.csproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <IsPackable>false</IsPackable>
+    <LangVersion>9.0</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>

OnTopic.AspNetCore.Mvc.Tests/TopicControllerTest.cs

@@ -73,7 +73,7 @@ public TopicControllerTest() {
         RouteData               = routes,
         ActionDescriptor        = new ControllerActionDescriptor()
       };
-      _context                  = new ControllerContext(actionContext);
+      _context                  = new(actionContext);
 
     }
 
@@ -131,11 +131,11 @@ public void SitemapController_Index_ReturnsSitemapXml() {
 
       var actionContext         = new ActionContext {
         HttpContext             = new DefaultHttpContext(),
-        RouteData               = new RouteData(),
+        RouteData               = new(),
         ActionDescriptor        = new ControllerActionDescriptor()
       };
       var controller            = new SitemapController(_topicRepository) {
-        ControllerContext       = new ControllerContext(actionContext)
+        ControllerContext       = new(actionContext)
       };
       var result                = controller.Index() as ContentResult;
       var model                 = result.Content as string;

OnTopic.AspNetCore.Mvc.Tests/ValidateTopicAttributeTest.cs

@@ -40,7 +40,7 @@ public static ActionExecutingContext GetActionExecutingContext(Controller contro
 
       var actionContext = new ActionContext(
         new DefaultHttpContext(),
-        new RouteData(),
+        new(),
         new ControllerActionDescriptor(),
         modelState
       );
@@ -63,10 +63,10 @@ public static ActionExecutingContext GetActionExecutingContext(Controller contro
     ///   Generates a barebones <see cref="ControllerContext"/> for testing a controller.
     /// </summary>
     public static ControllerContext GetControllerContext() =>
-      new ControllerContext(
-        new ActionContext() {
+      new(
+        new() {
           HttpContext               = new DefaultHttpContext(),
-          RouteData                 = new RouteData(),
+          RouteData                 = new(),
           ActionDescriptor          = new ControllerActionDescriptor()
         }
       );
@@ -78,7 +78,7 @@ public static ControllerContext GetControllerContext() =>
     ///   Generates a barebones <see cref="ControllerContext"/> for testing a controller.
     /// </summary>
     public static TopicController GetTopicController(Topic topic) =>
-      new TopicController(
+      new(
           new DummyTopicRepository(),
           new DummyTopicMappingService()
       ) {

OnTopic.AspNetCore.Mvc/Controllers/SitemapController.cs

@@ -146,7 +146,7 @@ public virtual ActionResult Index(bool indent = false, bool includeMetadata = fa
     /// <returns>A Sitemap.org sitemap.</returns>
     [Obsolete("The GenerateSitemap() method should not be public. It will be marked private in OnTopic Library 5.0.")]
     public virtual XDocument GenerateSitemap(Topic rootTopic, bool includeMetadata = false) =>
-      new XDocument(
+      new(
         new XElement(_sitemapNamespace + "urlset",
           from topic in rootTopic?.Children
           select AddTopic(topic, includeMetadata)

OnTopic.AspNetCore.Mvc/Controllers/TopicController.cs

@@ -122,7 +122,7 @@ public async virtual Task<IActionResult> IndexAsync(string path) {
     /// <returns>The created <see cref="TopicViewResult"/> object for the response.</returns>
     [NonAction]
     public virtual TopicViewResult TopicView(object model, string? viewName = null) =>
-      new TopicViewResult(ViewData, TempData, model, CurrentTopic?.ContentType, viewName);
+      new(ViewData, TempData, model, CurrentTopic?.ContentType, viewName);
 
   } //Class
 } //Namespace

OnTopic.Data.Sql/SqlTopicRepository.cs

@@ -269,7 +269,7 @@ public override int Save([NotNull]Topic topic, bool isRecursive = false, bool is
       | Attempt to resolve outstanding relationships
       \-----------------------------------------------------------------------------------------------------------------------*/
       foreach (var unresolvedTopic in unresolvedTopics) {
-        Save(unresolvedTopic, false, isDraft, connection, new List<Topic>(), version);
+        Save(unresolvedTopic, false, isDraft, connection, new(), version);
       }
 
       /*------------------------------------------------------------------------------------------------------------------------

OnTopic.Tests/AttributeValueCollectionTest.cs

@@ -453,7 +453,7 @@ public void Add_ValidAttributeValue_IsReturned() {
       var topic = TopicFactory.Create("Test", "Container");
 
       topic.Attributes.Remove("Key");
-      topic.Attributes.Add(new AttributeValue("Key", "NewKey", false));
+      topic.Attributes.Add(new("Key", "NewKey", false));
 
       Assert.AreEqual<string>("NewKey", topic.Key);
 
@@ -473,7 +473,7 @@ public void Add_ValidAttributeValue_IsReturned() {
     public void Add_InvalidAttributeValue_ThrowsException() {
       var topic = TopicFactory.Create("Test", "Container");
       topic.Attributes.Remove("Key");
-      topic.Attributes.Add(new AttributeValue("Key", "# ?"));
+      topic.Attributes.Add(new("Key", "# ?"));
     }
 
     /*==========================================================================================================================

OnTopic.Tests/BindingModels/ContentTypeDescriptorTopicBindingModel.cs

@@ -21,9 +21,9 @@ public class ContentTypeDescriptorTopicBindingModel : BasicTopicBindingModel {
 
     public ContentTypeDescriptorTopicBindingModel(string? key = null) : base(key, "ContentTypeDescriptor") { }
 
-    public List<RelatedTopicBindingModel> ContentTypes { get; } = new List<RelatedTopicBindingModel>();
+    public List<RelatedTopicBindingModel> ContentTypes { get; } = new();
 
-    public List<AttributeDescriptorTopicBindingModel> Attributes { get; } = new List<AttributeDescriptorTopicBindingModel>();
+    public List<AttributeDescriptorTopicBindingModel> Attributes { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/BindingModels/InvalidChildrenTopicBindingModel.cs

@@ -22,7 +22,7 @@ public class InvalidChildrenTopicBindingModel : BasicTopicBindingModel {
 
     public InvalidChildrenTopicBindingModel(string? key = null) : base(key, "Page") { }
 
-    public List<BasicTopicBindingModel> Children { get; } = new List<BasicTopicBindingModel>();
+    public List<BasicTopicBindingModel> Children { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/BindingModels/InvalidReferenceNameTopicBindingModel.cs

@@ -22,7 +22,7 @@ public class InvalidReferenceNameTopicBindingModel : BasicTopicBindingModel {
 
     public InvalidReferenceNameTopicBindingModel(string? key = null) : base(key, "Page") { }
 
-    public RelatedTopicBindingModel TopicReference { get; } = new RelatedTopicBindingModel();
+    public RelatedTopicBindingModel TopicReference { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/BindingModels/InvalidReferenceTypeTopicBindingModel.cs

@@ -25,7 +25,7 @@ public class InvalidReferenceTypeTopicBindingModel : BasicTopicBindingModel {
     public InvalidReferenceTypeTopicBindingModel(string? key = null) : base(key, "Page") { }
 
     [AttributeKey("TopicId")]
-    public TopicViewModel DerivedTopic { get; } = new TopicViewModel();
+    public TopicViewModel DerivedTopic { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/BindingModels/InvalidRelationshipBaseTypeTopicBindingModel.cs

@@ -24,7 +24,7 @@ public class InvalidRelationshipBaseTypeTopicBindingModel : BasicTopicBindingMod
 
     public InvalidRelationshipBaseTypeTopicBindingModel(string? key = null) : base(key, "ContentTypeDescriptor") { }
 
-    public List<TopicViewModel> ContentTypes { get; } = new List<TopicViewModel>();
+    public List<TopicViewModel> ContentTypes { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/BindingModels/InvalidRelationshipListTypeTopicBindingModel.cs

@@ -25,7 +25,7 @@ public class InvalidRelationshipListTypeTopicBindingModel : BasicTopicBindingMod
 
     public InvalidRelationshipListTypeTopicBindingModel(string? key = null) : base(key, "ContentTypeDescriptor") { }
 
-    public Dictionary<string, RelatedTopicBindingModel> ContentTypes { get; } = new Dictionary<string, RelatedTopicBindingModel>();
+    public Dictionary<string, RelatedTopicBindingModel> ContentTypes { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/BindingModels/InvalidRelationshipTypeTopicBindingModel.cs

@@ -26,7 +26,7 @@ public class InvalidRelationshipTypeTopicBindingModel : BasicTopicBindingModel {
     public InvalidRelationshipTypeTopicBindingModel(string? key = null) : base(key, "ContentTypeDescriptor") { }
 
     [Relationship(RelationshipType.NestedTopics)]
-    public List<RelatedTopicBindingModel> ContentTypes { get; } = new List<RelatedTopicBindingModel>();
+    public List<RelatedTopicBindingModel> ContentTypes { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/BindingModels/MapToParentTopicBindingModel.cs

@@ -19,13 +19,13 @@ namespace OnTopic.Tests.BindingModels {
   public class MapToParentTopicBindingModel : BasicTopicBindingModel {
 
     [MapToParent(AttributePrefix="")]
-    public ContactTopicBindingModel PrimaryContact { get; set; } = new ContactTopicBindingModel();
+    public ContactTopicBindingModel PrimaryContact { get; set; } = new();
 
     [MapToParent(AttributePrefix="Alternate")]
-    public EmailTopicBindingModel AlternateContact { get; set; } = new EmailTopicBindingModel();
+    public EmailTopicBindingModel AlternateContact { get; set; } = new();
 
     [MapToParent]
-    public EmailTopicBindingModel BillingContact { get; set; } = new EmailTopicBindingModel();
+    public EmailTopicBindingModel BillingContact { get; set; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ReverseTopicMappingServiceTest.cs

@@ -227,7 +227,7 @@ public async Task Map_Relationships_ReturnsMappedTopic() {
 
       for (var i = 0; i < 3; i++) {
         bindingModel.ContentTypes.Add(
-          new Models.RelatedTopicBindingModel() {
+          new() {
             UniqueKey = contentTypes[i].GetUniqueKey()
           }
         );
@@ -290,7 +290,7 @@ public async Task Map_TopicReferences_ReturnsMappedTopic() {
       var mappingService        = new ReverseTopicMappingService(_topicRepository);
 
       var bindingModel          = new ReferenceTopicBindingModel("Test") {
-        DerivedTopic            = new RelatedTopicBindingModel() {
+        DerivedTopic            = new() {
           UniqueKey             = _topicRepository.Load("Root:Configuration:ContentTypes:Attributes:Title").GetUniqueKey()
         }
       };
@@ -394,7 +394,7 @@ public async Task Map_InvalidParentProperty_ThrowsInvalidOperationException() {
       var mappingService        = new ReverseTopicMappingService(_topicRepository);
 
       var bindingModel          = new InvalidParentTopicBindingModel("Test") {
-        Parent                  = new BasicTopicBindingModel("Test", "Page")
+        Parent                  = new("Test", "Page")
       };
 
       var target = await mappingService.MapAsync(bindingModel).ConfigureAwait(false);

OnTopic.Tests/TopicMappingServiceTest.cs

@@ -236,8 +236,8 @@ public async Task Map_NullablePropertiesWithInvalidValues_ReturnsValues() {
       Assert.AreEqual<int?>(43, target.NullableInteger);
       Assert.AreEqual<double?>(3.14159265359, target.NullableDouble);
       Assert.AreEqual<bool?>(true, target.NullableBoolean);
-      Assert.AreEqual<DateTime?>(new DateTime(1976, 10, 15), target.NullableDateTime);
-      Assert.AreEqual<Uri?>(new Uri("/Web/Path/File?Query=String", UriKind.RelativeOrAbsolute), target.NullableUrl);
+      Assert.AreEqual<DateTime?>(new(1976, 10, 15), target.NullableDateTime);
+      Assert.AreEqual<Uri?>(new("/Web/Path/File?Query=String", UriKind.RelativeOrAbsolute), target.NullableUrl);
 
       Assert.AreEqual<string?>(topic.Title, target.Title);
       Assert.AreEqual<bool?>(target.IsHidden, target.IsHidden);
@@ -676,7 +676,7 @@ public async Task Map_CompatibleProperties_MapObjectReference() {
 
       var topic                 = (TextAttribute)TopicFactory.Create("Attribute", "TextAttribute");
 
-      topic.VersionHistory.Add(new DateTime(1976, 10, 15, 9, 30, 00));
+      topic.VersionHistory.Add(new(1976, 10, 15, 9, 30, 00));
 
       var target                = await _mappingService.MapAsync<CompatiblePropertyTopicViewModel>(topic).ConfigureAwait(false);
 

OnTopic.Tests/TypeMemberInfoCollectionTest.cs

@@ -213,8 +213,8 @@ public void SetPropertyValue_DateTime_SetsValue() {
       );
 
       Assert.IsTrue(isDateSet);
-      Assert.AreEqual<DateTime>(new DateTime(2008, 6, 3), topic.LastModified);
-      Assert.AreEqual<DateTime>(new DateTime(2008, 6, 3), lastModified);
+      Assert.AreEqual<DateTime>(new(2008, 6, 3), topic.LastModified);
+      Assert.AreEqual<DateTime>(new(2008, 6, 3), lastModified);
 
     }
 

OnTopic.Tests/ViewModels/AmbiguousRelationTopicViewModel.cs

@@ -28,7 +28,7 @@ namespace OnTopic.Tests.ViewModels {
   public class AmbiguousRelationTopicViewModel: KeyOnlyTopicViewModel {
 
     [Relationship("AmbiguousRelationship", Type=RelationshipType.IncomingRelationship)]
-    public List<KeyOnlyTopicViewModel> RelationshipAlias { get; } = new List<KeyOnlyTopicViewModel>();
+    public List<KeyOnlyTopicViewModel> RelationshipAlias { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/CircularTopicViewModel.cs

@@ -23,7 +23,7 @@ public class CircularTopicViewModel {
     public CircularTopicViewModel? Parent { get; set; }
 
     [Follow(Relationships.Children | Relationships.Parents)]
-    public List<CircularTopicViewModel> Children { get; } = new List<CircularTopicViewModel>();
+    public List<CircularTopicViewModel> Children { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/DescendentTopicViewModel.cs

@@ -26,8 +26,7 @@ namespace OnTopic.Tests.ViewModels {
   public class DescendentTopicViewModel: TopicViewModel {
 
     [Follow(Relationships.Children)]
-    public TopicViewModelCollection<DescendentTopicViewModel> Children { get; }
-      = new TopicViewModelCollection<DescendentTopicViewModel>();
+    public TopicViewModelCollection<DescendentTopicViewModel> Children { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/FilteredTopicViewModel.cs

@@ -22,7 +22,7 @@ public class FilteredTopicViewModel {
 
     [FilterByAttribute("ContentType", "Page")]
     [FilterByAttribute("SomeAttribute", "ValueA")]
-    public TopicViewModelCollection<TopicViewModel> Children { get; } = new TopicViewModelCollection<TopicViewModel>();
+    public TopicViewModelCollection<TopicViewModel> Children { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/FlattenChildrenTopicViewModel.cs

@@ -21,7 +21,7 @@ namespace OnTopic.Tests.ViewModels {
   public class FlattenChildrenTopicViewModel {
 
     [Flatten]
-    public List<FlattenChildrenTopicViewModel> Children { get; } = new List<FlattenChildrenTopicViewModel>();
+    public List<FlattenChildrenTopicViewModel> Children { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/MapToParentTopicViewModel.cs

@@ -19,13 +19,13 @@ namespace OnTopic.Tests.ViewModels {
   public class MapToParentTopicViewModel {
 
     [MapToParent(AttributePrefix = "")]
-    public KeyOnlyTopicViewModel? Primary { get; set; } = new KeyOnlyTopicViewModel();
+    public KeyOnlyTopicViewModel? Primary { get; set; } = new();
 
     [MapToParent(AttributePrefix = "Aliased")]
-    public KeyOnlyTopicViewModel? Alternate { get; set; } = new KeyOnlyTopicViewModel();
+    public KeyOnlyTopicViewModel? Alternate { get; set; } = new();
 
     [MapToParent]
-    public KeyOnlyTopicViewModel? Ancillary { get; set; } = new KeyOnlyTopicViewModel();
+    public KeyOnlyTopicViewModel? Ancillary { get; set; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/Metadata/ContentTypeDescriptorTopicViewModel.cs

@@ -20,13 +20,11 @@ namespace OnTopic.Tests.ViewModels.Metadata {
   /// </remarks>
   public class ContentTypeDescriptorTopicViewModel {
 
-    public List<AttributeDescriptorTopicViewModel> AttributeDescriptors
-      { get; } = new List<AttributeDescriptorTopicViewModel>();
+    public List<AttributeDescriptorTopicViewModel> AttributeDescriptors { get; } = new();
 
     [Relationship(RelationshipType.MappedCollection)]
     [Follow(Relationships.None)]
-    public List<ContentTypeDescriptorTopicViewModel> PermittedContentTypes
-      { get; } = new List<ContentTypeDescriptorTopicViewModel>();
+    public List<ContentTypeDescriptorTopicViewModel> PermittedContentTypes { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/MetadataLookupTopicViewModel.cs

@@ -20,7 +20,7 @@ namespace OnTopic.Tests.ViewModels {
   public class MetadataLookupTopicViewModel {
 
     [Metadata("Categories")]
-    public TopicViewModelCollection<TopicViewModel> Categories { get; } = new TopicViewModelCollection<TopicViewModel>();
+    public TopicViewModelCollection<TopicViewModel> Categories { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/NestedTopicViewModel.cs

@@ -18,7 +18,7 @@ namespace OnTopic.Tests.ViewModels {
   /// </remarks>
   public class NestedTopicViewModel {
 
-    public List<KeyOnlyTopicViewModel> Categories { get; } = new List<KeyOnlyTopicViewModel>();
+    public List<KeyOnlyTopicViewModel> Categories { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/RelatedEntityTopicViewModel.cs

@@ -25,7 +25,7 @@ namespace OnTopic.Tests.ViewModels {
   /// </remarks>
   public class RelatedEntityTopicViewModel: KeyOnlyTopicViewModel {
 
-    public Collection<Topic> RelatedTopics { get; } = new Collection<Topic>();
+    public Collection<Topic> RelatedTopics { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/RelationTopicViewModel.cs

@@ -26,7 +26,7 @@ namespace OnTopic.Tests.ViewModels {
   public class RelationTopicViewModel: KeyOnlyTopicViewModel {
 
     [Follow(Relationships.Children)]
-    public List<RelationTopicViewModel> Cousins { get; } = new List<RelationTopicViewModel>();
+    public List<RelationTopicViewModel> Cousins { get; } = new();
 
   } //Class
 } //Namespace

OnTopic.Tests/ViewModels/RelationWithChildrenTopicViewModel.cs

@@ -26,7 +26,7 @@ namespace OnTopic.Tests.ViewModels {
   public class RelationWithChildrenTopicViewModel: RelationTopicViewModel {
 
     [Follow(Relationships.Relationships)]
-    public List<RelationWithChildrenTopicViewModel> Children { get; } = new List<RelationWithChildrenTopicViewModel>();
+    public List<RelationWithChildrenTopicViewModel> Children { get; } = new();
 
   } //Class
 } //Namespace