Prefer is for type checking, where possible

Prefer `is` over either `Equals(typeof())` or `IsAssignableFrom()`, assuming a constant type and a positive check.

Author: JeremyCaney

OnTopic/Attributes/AttributeValueConverter.cs

@@ -128,24 +128,22 @@ internal static class AttributeValueConverter {
       /*------------------------------------------------------------------------------------------------------------------------
       | Handle type-specific rules
       \-----------------------------------------------------------------------------------------------------------------------*/
-      var type                  = value.GetType();
-
-      if (type.Equals(typeof(string))) {
+      if (value is string) {
         return (string)value;
       }
-      else if (type.Equals(typeof(bool)) || type.Equals(typeof(bool?))) {
+      else if (value is bool) {
         return ((bool)value) ? "1" : "0";
       }
-      else if (type.Equals(typeof(int)) || type.Equals(typeof(int?))) {
+      else if (value is int) {
         return ((int)value).ToString(CultureInfo.InvariantCulture);
       }
-      else if (type.Equals(typeof(double)) || type.Equals(typeof(double?))) {
+      else if (value is double) {
         return ((double)value).ToString(CultureInfo.InvariantCulture);
       }
-      else if (type.Equals(typeof(DateTime)) || type.Equals(typeof(DateTime?))) {
+      else if (value is DateTime) {
         return ((DateTime)value).ToString(CultureInfo.InvariantCulture);
       }
-      else if (type.Equals(typeof(Uri))) {
+      else if (value is Uri) {
         return ((Uri)value).ToString();
       }
 

OnTopic/Mapping/TopicMappingService.cs

@@ -294,7 +294,7 @@ private async Task<object> MapAsync(
       /*------------------------------------------------------------------------------------------------------------------------
       | Handle topics
       \-----------------------------------------------------------------------------------------------------------------------*/
-      if (typeof(Topic).IsAssignableFrom(target.GetType())) {
+      if (target is Topic) {
         return topic;
       }
 
@@ -856,7 +856,7 @@ private IList<Topic> GetSourceCollection(Topic source, AssociationTypes associat
         if (
           sourceProperty?.GetValue(source) is IList sourcePropertyValue &&
           sourcePropertyValue.Count > 0 &&
-          typeof(Topic).IsAssignableFrom(sourcePropertyValue[0]?.GetType())
+          sourcePropertyValue[0] is Topic
         ) {
           listSource = getCollection(
             CollectionType.MappedCollection,

OnTopic/Metadata/ContentTypeDescriptorCollection.cs

@@ -79,7 +79,7 @@ public void Refresh(ContentTypeDescriptor? rootContentType) {
       | Add all ContentTypeDescriptors to collection
       \-----------------------------------------------------------------------------------------------------------------------*/
       var contentTypeDescriptors = rootContentType
-        .FindAll(t => typeof(ContentTypeDescriptor).IsAssignableFrom(t.GetType()))
+        .FindAll(t => t is ContentTypeDescriptor)
         .Cast<ContentTypeDescriptor>();
       foreach (var contentType in contentTypeDescriptors) {
         Add((ContentTypeDescriptor)contentType);

OnTopic/Querying/TopicExtensions.cs

@@ -288,7 +288,7 @@ public static ReadOnlyTopicCollection FindAllByAttribute(this Topic topic, strin
       \-----------------------------------------------------------------------------------------------------------------------*/
       var contentTypeDescriptor = rootContentType?.FindFirst(t =>
         t.Key.Equals(topic.ContentType, StringComparison.OrdinalIgnoreCase) &&
-        t.GetType().IsAssignableFrom(typeof(ContentTypeDescriptor))
+        t is ContentTypeDescriptor
       ) as ContentTypeDescriptor;
 
       /*------------------------------------------------------------------------------------------------------------------------