Finish programming guide.

Author: BillWagner

docs/csharp/programming-guide/classes-and-structs/snippets/how-to-implement-and-call-a-custom-extension-method/Program.cs

@@ -0,0 +1,27 @@
+using CustomExtensions;
+
+string s = "The quick brown fox jumped over the lazy dog.";
+// Call the method as if it were an
+// instance method on the type. Note that the first
+// parameter is not specified by the calling code.
+int i = s.WordCount();
+System.Console.WriteLine($"Word count of s is {i}");
+
+
+namespace CustomExtensions
+{
+    // Extension methods must be defined in a static class.
+    public static class StringExtension
+    {
+        extension(string str)
+        {
+            // This is the extension member.
+            // The `str` parameter is declared on the extension declaration.
+            public int WordCount()
+            {
+                return str.Split(new char[] { ' ', '.', '?' }, StringSplitOptions.RemoveEmptyEntries).Length;
+            }
+        }
+    }
+}
+

docs/csharp/programming-guide/classes-and-structs/snippets/how-to-implement-and-call-a-custom-extension-method/how-to-implement-and-call-a-custom-extension-method.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

docs/csharp/programming-guide/generics/constraints-on-type-parameters.md

@@ -1,7 +1,7 @@
 ---
 title: "Constraints on type parameters"
 description: Learn about constraints on type parameters. Constraints tell the compiler what capabilities a type argument must have.
-ms.date: 10/10/2025
+ms.date: 11/25/2025
 f1_keywords:
   - "defaultconstraint_CSharpKeyword"
   - "notnull_CSharpKeyword"

docs/csharp/programming-guide/generics/snippets/GenericWhereConstraints.cs

@@ -175,20 +175,25 @@ unsafe public static byte[] ToByteArray<T>(this T argument) where T : unmanaged
         // </Snippet15>
 
         // <Snippet16>
-        public static TDelegate? TypeSafeCombine<TDelegate>(this TDelegate source, TDelegate target)
-            where TDelegate : System.Delegate
-            => Delegate.Combine(source, target) as TDelegate;
+        extension<TDelegate>(TDelegate source) where TDelegate : System.Delegate
+        {
+            public TDelegate? TypeSafeCombine(TDelegate target)
+                => Delegate.Combine(source, target) as TDelegate;
+        }
         // </Snippet16>
 
         // <Snippet18>
-        public static Dictionary<int, string> EnumNamedValues<T>() where T : System.Enum
+        extension<T>(T) where T : System.Enum
         {
-            var result = new Dictionary<int, string>();
-            var values = Enum.GetValues(typeof(T));
+            public static Dictionary<int, string> EnumNamedValues()
+            {
+                var result = new Dictionary<int, string>();
+                var values = Enum.GetValues(typeof(T));
 
-            foreach (int item in values)
-                result.Add(item, Enum.GetName(typeof(T), item)!);
-            return result;
+                foreach (int item in values)
+                    result.Add(item, Enum.GetName(typeof(T), item)!);
+                return result;
+            }
         }
         // </Snippet18>
     }

docs/csharp/programming-guide/generics/snippets/generics.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>