From e2c536bee7f7c2d759a945562df25ae36e445c5b Mon Sep 17 00:00:00 2001
From: Bill Wagner <wiwagn@microsoft.com>
Date: Mon, 27 Jan 2025 14:01:14 -0500
Subject: [PATCH 1/2] Add example of `{ }` pattern

Fixes #43926

You can match a property against the `{ }` pattern to match any non-null property. Add an example of that construct.
---
 .../functional/pattern-matching.md            | 10 ++++++++-
 .../functional/snippets/patterns/Program.cs   | 21 ++++++++++++++++++-
 .../snippets/patterns/patterns.csproj         |  2 +-
 3 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/docs/csharp/fundamentals/functional/pattern-matching.md b/docs/csharp/fundamentals/functional/pattern-matching.md
index a3b24fc943169..9754d42a1ca81 100644
--- a/docs/csharp/fundamentals/functional/pattern-matching.md
+++ b/docs/csharp/fundamentals/functional/pattern-matching.md
@@ -1,7 +1,7 @@
 ---
 title: Pattern matching overview
 description: "Learn about pattern matching expressions in C#"
-ms.date: 03/13/2024
+ms.date: 01/27/2025
 ---
 
 # Pattern matching overview
@@ -78,6 +78,14 @@ The first two arms examine two properties of the `Order`. The third examines onl
 
 The preceding code demonstrates the [*positional pattern*](../../language-reference/operators/patterns.md#positional-pattern) where the properties are deconstructed for the expression.
 
+You can also match a property against `{ }`, which matches any non-null value. Consider the following declaration, which stores measurements with an optional annotation:
+
+:::code language="csharp" source="snippets/patterns/Program.cs" ID="Observation":::
+
+You can test if a given observation has a non-null annotation using the following pattern matching expression:
+
+:::code language="csharp" source="snippets/patterns/Program.cs" ID="NotNullPropertyPattern":::
+
 ## List patterns
 
 You can check elements in a list or an array using a *list pattern*. A [list pattern](../../language-reference/operators/patterns.md#list-patterns) provides a means to apply a pattern to any element of a sequence. In addition, you can apply the *discard pattern* (`_`) to match any element, or apply a *slice pattern* to match zero or more elements.
diff --git a/docs/csharp/fundamentals/functional/snippets/patterns/Program.cs b/docs/csharp/fundamentals/functional/snippets/patterns/Program.cs
index 6045d2b9de9f3..7d6e8f85e2496 100644
--- a/docs/csharp/fundamentals/functional/snippets/patterns/Program.cs
+++ b/docs/csharp/fundamentals/functional/snippets/patterns/Program.cs
@@ -8,11 +8,13 @@ static void Main(string[] args)
 
         NullReferenceCheck();
 
-        var sequence = new List<int> {1,2,3,4,5,6,7};
+        var sequence = new List<int> { 1, 2, 3, 4, 5, 6, 7 };
         var middle = MidPoint(sequence);
         Console.WriteLine(middle);
 
         ListPattern.Example();
+
+        NotNullProperty(new Observation(42, "C", "Temperature"));
     }
 
     // <MidPoint>
@@ -65,4 +67,21 @@ private static void NullCheck()
         }
         // </NullableCheck>
     }
+
+    private static void NotNullProperty(Observation observation)
+    {
+        // <NotNullPropertyPattern>
+        if (observation.Annotation is { })
+        {
+            Console.WriteLine($"Observation description: {observation.Annotation}");
+        }
+        // <NotNullPropertyPattern>
+    }
+
+    // <Observation>
+    public record class Observation(int Value, string Units, string Name)
+    {
+        public string? Annotation { get; set; }
+    }
+    // </Observation>
 }
diff --git a/docs/csharp/fundamentals/functional/snippets/patterns/patterns.csproj b/docs/csharp/fundamentals/functional/snippets/patterns/patterns.csproj
index f704bf4988fa6..58be7ac77af37 100644
--- a/docs/csharp/fundamentals/functional/snippets/patterns/patterns.csproj
+++ b/docs/csharp/fundamentals/functional/snippets/patterns/patterns.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>

From 632c804c838277324b2d2eb05c79f65d748f66bf Mon Sep 17 00:00:00 2001
From: Bill Wagner <wiwagn@microsoft.com>
Date: Mon, 27 Jan 2025 14:27:42 -0500
Subject: [PATCH 2/2] fix snippet marker

---
 .../csharp/fundamentals/functional/snippets/patterns/Program.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/csharp/fundamentals/functional/snippets/patterns/Program.cs b/docs/csharp/fundamentals/functional/snippets/patterns/Program.cs
index 7d6e8f85e2496..5e61209361470 100644
--- a/docs/csharp/fundamentals/functional/snippets/patterns/Program.cs
+++ b/docs/csharp/fundamentals/functional/snippets/patterns/Program.cs
@@ -75,7 +75,7 @@ private static void NotNullProperty(Observation observation)
         {
             Console.WriteLine($"Observation description: {observation.Annotation}");
         }
-        // <NotNullPropertyPattern>
+        // </NotNullPropertyPattern>
     }
 
     // <Observation>