update delegate and events samples (#80)

For dotnet/docs#87

There were two major changes to update these samples.
1. UPgrade from project.json to csproj files.
1. Add snippet tags for including into the main topics.

Author: BillWagner

csharp/delegates-and-events/FileLogger.cs

@@ -3,34 +3,38 @@
 
 namespace DelegatesAndEvents
 {
-public class FileLogger
-{
-    private readonly string logPath;
-    public FileLogger(string path)
-    {
-        logPath = path;
-        Logger.WriteMessage += LogMessage;
-    }
-    
-    public void DetachLog() => Logger.WriteMessage -= LogMessage;
-    // make sure this can't throw.
-    private void LogMessage(string msg)
+    // <SnippetFileLogger>
+    public class FileLogger
     {
-        try {
-            using (var log = File.AppendText(logPath))
+        private readonly string logPath;
+        public FileLogger(string path)
+        {
+            logPath = path;
+            Logger.WriteMessage += LogMessage;
+        }
+
+        public void DetachLog() => Logger.WriteMessage -= LogMessage;
+        // make sure this can't throw.
+        private void LogMessage(string msg)
+        {
+            try
             {
-                log.WriteLine(msg);
-                log.Flush();
+                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.
             }
-        } 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

@@ -4,6 +4,7 @@ namespace DelegatesAndEvents
 {
 
     // Logger implementation two
+    // <SnippetSeverity>
     public enum Severity
     {
         Verbose,
@@ -13,7 +14,9 @@ public enum Severity
         Error,
         Critical
     }
+    // </SnippetSeverity>
 
+    // <SnippetLoggerFinal>
     public static class Logger
     {
         public static Action<string> WriteMessage;
@@ -26,11 +29,42 @@ public static void LogMessage(Severity s, string component, string msg)
                 return;
 
             var outputMsg = $"{DateTime.Now}\t{s}\t{component}\t{msg}";
-            // Assumes that the WriteMessage delegate must not be null:
             WriteMessage(outputMsg);
-            // Alternative invoke syntax, for when the delegate
-            // may not have any methods attached:
-            WriteMessage?.Invoke(outputMsg);
         }
     }
-}
+    // </SnippetLoggerFinal>
+}
+
+namespace ImplementationOne
+{
+    // <SnippetFirstImplementation>
+    public static class Logger
+    {
+        public static Action<string> WriteMessage;
+
+        public static void LogMessage(string msg)
+        {
+            WriteMessage(msg);
+        }
+    }
+    // </SnippetFirstImplementation>
+
+}
+
+namespace ImplementationTwo
+{
+    using DelegatesAndEvents;
+
+    // <SnippetLoggerTwo>
+    public static class Logger
+    {
+        public static Action<string> WriteMessage;
+
+        public static void LogMessage(Severity s, string component, string msg)
+        {
+            var outputMsg = $"{DateTime.Now}\t{s}\t{component}\t{msg}";
+            WriteMessage(outputMsg);
+        }
+    }
+    // </SnippetLoggerTwo>
+}

csharp/delegates-and-events/Program.cs

@@ -4,15 +4,21 @@ namespace DelegatesAndEvents
 {
     public class Program
     {
+        // <SnippetLogToConsole>
         public static void LogToConsole(string message)
         {
             Console.Error.WriteLine(message);
         }
+        // </SnippetLogToConsole>
 
         public static void Main(string[] args)
         {
+            // <SnippetConnectDelegate>
             Logger.WriteMessage += LogToConsole;
+            // </SnippetConnectDelegate>
+            // <SnippetFileLogger>
             var file = new FileLogger("log.txt");
+            // </SnippetFileLogger>
 
             Logger.LogMessage(Severity.Warning, "Console", "This is a warning message");
 

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

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp1.0</TargetFramework>
+    <DebugType>portable</DebugType>
+    <AssemblyName>delegates-and-events</AssemblyName>
+    <OutputType>Exe</OutputType>
+    <PackageId>delegates-and-events</PackageId>
+    <PackageTargetFallback>$(PackageTargetFallback);dnxcore50</PackageTargetFallback>
+    <RuntimeFrameworkVersion>1.0.4</RuntimeFrameworkVersion>
+  </PropertyGroup>
+
+</Project>

csharp/delegates-and-events/log.txt

@@ -15,27 +15,33 @@ static void Main(string[] args)
             var lister = new FileSearcher();
             int filesFound = 0;
 
+            // <SnippetDeclareEventHandler>
             EventHandler<FileFoundArgs> onFileFound = (sender, eventArgs) =>
             {
                 Console.WriteLine(eventArgs.FoundFile);
                 filesFound++;
-                //eventArgs.CancelRequested = true;
             };
 
             lister.FileFound += onFileFound;
+            // </SnippetDeclareEventHandler>
 
+            // <SnippetSearch>
             lister.DirectoryChanged += (sender, eventArgs) =>
             {
                 Console.Write($"Entering '{eventArgs.CurrentSearchDirectory}'.");
                 Console.WriteLine($" {eventArgs.CompletedDirs} of {eventArgs.TotalDirs} completed...");
             };
+            // </SnippetSearch>
 
             lister.Search(".", "*.dll", true);
 
+            // <SnippetRemoveHandler>
             lister.FileFound -= onFileFound;
+            // </SnippetRemoveHandler>
         }
     }
 
+    // <SnippetEventArgs>
     public class FileFoundArgs : EventArgs
     {
         public string FoundFile { get; }
@@ -46,7 +52,9 @@ public FileFoundArgs(string fileName)
             FoundFile = fileName;
         }
     }
+    // </SnippetEventArg>
 
+    // <SnippetSearchDirEventArgs>
     internal struct SearchDirectoryArgs 
     {
         internal string CurrentSearchDirectory { get; }
@@ -60,16 +68,23 @@ internal SearchDirectoryArgs(string dir, int totalDirs, int completedDirs)
             CompletedDirs = completedDirs;
         }
     }
+    // </SnippetSearchDirEventArgs>
+
     public class FileSearcher
     {
+        // <SnippetDeclareEvent>
         public event EventHandler<FileFoundArgs> FileFound;
+        // </SnippetDeclareEvent>
+        // <SnippetDeclareSearchEvent>
         internal event EventHandler<SearchDirectoryArgs> DirectoryChanged
         {
             add { directoryChanged += value; }
             remove { directoryChanged -= value; }
         }
         private EventHandler<SearchDirectoryArgs> directoryChanged;
+        // </SnippetDeclareSearchEvent>
 
+        // <SnippetFinalImplementation>
         public void Search(string directory, string searchPattern, bool searchSubDirs = false)
         {
             if (searchSubDirs)
@@ -105,5 +120,38 @@ private void SearchDirectory(string directory, string searchPattern)
                     break;
             }
         }
+        // </SnippetFinalImplementation>
+    }
+}
+
+namespace VersionOne
+{
+    // <SnippetEventArgsV1>
+    public class FileFoundArgs : EventArgs
+    {
+        public string FoundFile { get; }
+        public bool CancelRequested { get; set; }
+
+        public FileFoundArgs(string fileName)
+        {
+            FoundFile = fileName;
+        }
     }
+    // </SnippetEventArgV1>
+
+    // <SnippetFileSearcherV1>
+    public class FileSearcher
+    {
+        public event EventHandler<FileFoundArgs> FileFound;
+
+        public void Search(string directory, string searchPattern)
+        {
+            foreach (var file in Directory.EnumerateFiles(directory, searchPattern))
+            {
+                FileFound?.Invoke(this, new FileFoundArgs(file));
+            }
+        }
+    }
+    // </SnippetFileSearcherV1>
+
 }

csharp/delegates-and-events/project.json

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp1.0</TargetFramework>
+    <DebugType>portable</DebugType>
+    <AssemblyName>events</AssemblyName>
+    <OutputType>Exe</OutputType>
+    <PackageId>events</PackageId>
+    <PackageTargetFallback>$(PackageTargetFallback);dnxcore50</PackageTargetFallback>
+    <RuntimeFrameworkVersion>1.0.4</RuntimeFrameworkVersion>
+  </PropertyGroup>
+
+</Project>