Update samples used in delegates articles (#7028)

* Update samples used in delegates articles

Contributes to dotnet/docs#45199

These samples haven't been updated since .NET 7.

It's time to update them while updating the related articles.

* Update csharp/events/Program.cs

* Apply suggestions from code review

Co-authored-by: David Pine <[email protected]>

---------

Co-authored-by: David Pine <[email protected]>

Author: BillWagner

csharp/delegates-and-events/FileLogger.cs

@@ -1,40 +1,34 @@
-using System;
-using System.IO;
+namespace DelegatesAndEvents;
 
-namespace DelegatesAndEvents
+public class FileLogger
 {
-    // <SnippetFileLogger>
-    public class FileLogger
+    private readonly string _logPath;
+    public FileLogger(string path)
     {
-        private readonly string logPath;
-        public FileLogger(string path)
-        {
-            logPath = path;
-            Logger.WriteMessage += LogMessage;
-        }
+        _logPath = path;
+        Logger.WriteMessage += LogMessage;
+    }
 
-        public void DetachLog() => Logger.WriteMessage -= LogMessage;
-        // make sure this can't throw.
-        private void LogMessage(string msg)
+    public void DetachLog() => Logger.WriteMessage -= LogMessage;
+    // make sure this can't throw.
+    private void LogMessage(string msg)
+    {
+        try
         {
-            try
+            using (var log = File.AppendText(_logPath))
             {
-                using (var log = File.AppendText(logPath))
-                {
-                    log.WriteLine(msg);
-                    log.Flush();
-                }
-            }
-            catch (Exception)
-            {
-                // Hmm. We caught an exception while
-                // logging. We can't really log the
-                // problem (since it's the log that's failing).
-                // So, while normally, catching an exception
-                // and doing nothing isn't wise, it's really the
-                // only reasonable option here.
+                log.WriteLine(msg);
+                log.Flush();
             }
         }
+        catch (Exception)
+        {
+            // Hmm. We caught an exception while
+            // logging. We can't really log the
+            // problem (since it's the log that's failing).
+            // So, while normally, catching an exception
+            // and doing nothing isn't wise, it's really the
+            // only reasonable option here.
+        }
     }
-    // </SnippetFileLogger>
 }

csharp/delegates-and-events/Logger.cs

@@ -1,69 +1,27 @@
-using System;
+namespace DelegatesAndEvents;
 
-namespace DelegatesAndEvents
+public enum Severity
 {
-
-    // Logger implementation two
-    // <SnippetSeverity>
-    public enum Severity
-    {
-        Verbose,
-        Trace,
-        Information,
-        Warning,
-        Error,
-        Critical
-    }
-    // </SnippetSeverity>
-
-    // <SnippetLoggerFinal>
-    public static class Logger
-    {
-        public static Action<string> WriteMessage;
-
-        public static Severity LogLevel { get; set; } = Severity.Warning;
-
-        public static void LogMessage(Severity s, string component, string msg)
-        {
-            if (s < LogLevel)
-                return;
-
-            var outputMsg = $"{DateTime.Now}\t{s}\t{component}\t{msg}";
-            WriteMessage(outputMsg);
-        }
-    }
-    // </SnippetLoggerFinal>
+    Verbose,
+    Trace,
+    Information,
+    Warning,
+    Error,
+    Critical
 }
 
-namespace ImplementationOne
+public static class Logger
 {
-    // <SnippetFirstImplementation>
-    public static class Logger
-    {
-        public static Action<string> WriteMessage;
+    public static Action<string>? WriteMessage;
 
-        public static void LogMessage(string msg)
-        {
-            WriteMessage(msg);
-        }
-    }
-    // </SnippetFirstImplementation>
-}
-
-namespace ImplementationTwo
-{
-    using DelegatesAndEvents;
+    public static Severity LogLevel { get; set; } = Severity.Warning;
 
-    // <SnippetLoggerTwo>
-    public static class Logger
+    public static void LogMessage(Severity s, string component, string msg)
     {
-        public static Action<string> WriteMessage;
+        if ((s < LogLevel) || (WriteMessage is null))
+            return;
 
-        public static void LogMessage(Severity s, string component, string msg)
-        {
-            var outputMsg = $"{DateTime.Now}\t{s}\t{component}\t{msg}";
-            WriteMessage(outputMsg);
-        }
+        var outputMsg = $"{DateTime.Now}\t{s}\t{component}\t{msg}";
+        WriteMessage(outputMsg);
     }
-    // </SnippetLoggerTwo>
 }

csharp/delegates-and-events/Program.cs

@@ -1,24 +1,11 @@
-using System;
+using DelegatesAndEvents;
 
-namespace DelegatesAndEvents
-{
-    public class Program
-    {
-        public static void Main(string[] args)
-        {
-            // <SnippetConnectDelegate>
-            Logger.WriteMessage += LoggingMethods.LogToConsole;
-            // </SnippetConnectDelegate>
-            // <SnippetFileLogger>
-            var file = new FileLogger("log.txt");
-            // </SnippetFileLogger>
+Logger.WriteMessage += LoggingMethods.LogToConsole;
+var file = new FileLogger("log.txt");
 
-            Logger.LogMessage(Severity.Warning, "Console", "This is a warning message");
+Logger.LogMessage(Severity.Warning, "Console", "This is a warning message");
 
-            Logger.LogMessage(Severity.Information, "Console", "Information message one");
-            Logger.LogLevel = Severity.Information;
+Logger.LogMessage(Severity.Information, "Console", "Information message one");
+Logger.LogLevel = Severity.Information;
 
-            Logger.LogMessage(Severity.Information, "Console", "Information message two");
-        }
-    }
-}
+Logger.LogMessage(Severity.Information, "Console", "Information message two");

csharp/delegates-and-events/delegates-and-events.csproj

@@ -1,8 +1,10 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <OutputType>Exe</OutputType>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
 
 </Project>