revert HelloWorld sample code changes

Author: lambdageek

src/mono/sample/HelloWorld/Program.cs

@@ -2,112 +2,18 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-using System.Runtime.CompilerServices;
 
-#if false
-
-public class MyBox<T>
-{
-    private T _value;
-    public T Value { get => _value; private set { _value = value; }}
-    public MyBox(T inp) { Value = inp; }
-}
-
-public class SimpleBox
+namespace HelloWorld
 {
-        private decimal _value;
-        public decimal Value { get => _value; private set { _value = value;}}
-        public SimpleBox(decimal inp) { Value = inp;}
-}
-
-public class Program
-{
-    public static void Main()
+    internal class Program
     {
-        var sbox = new SimpleBox((decimal)-5);
-        RunSimple(sbox, (decimal)20);
-        Console.WriteLine ("20 = {0}", sbox.Value);
-        var box = new MyBox<string>("xyz");
-        RunItAgain<string>(box, "hjk");
-        Console.WriteLine ("hjk = {0}", box.Value);
-        var box2 = new MyBox<decimal>((decimal)-2);
-        RunItAgain<decimal>(box2, (decimal)10.0);
-        Console.WriteLine (box2.Value);
-        RunIt<string>(box, "abc");
-        Console.WriteLine ("abc = {0}", box.Value);
-    }
-
-    [MethodImpl(MethodImplOptions.NoInlining)]
-    public static void RunIt<H> (MyBox<H> dest, H input)
-    {
-        ref H boxWriter = ref AccessBox(dest);
-        boxWriter = input;
-    }
-
-    [MethodImpl(MethodImplOptions.NoInlining)]
-    public static void RunItAgain<S> (MyBox<S> dest, S input)
-    {
-        ref S boxWriter = ref AccessHelper<S>.AccessBox2(dest);
-        boxWriter = input;
-    }
-
-    [UnsafeAccessor(UnsafeAccessorKind.Field, Name="_value")]
-    private static extern ref W AccessBox<W>(MyBox<W> x);
-
-    [MethodImpl(MethodImplOptions.NoInlining)]
-    private static void RunSimple(SimpleBox s, decimal input)
-    {
-        ref decimal boxWriter = ref SimpleHelper.AccessSimpleBox(s);
-        boxWriter = input;
-    }
-}
-
-public class AccessHelper<Q>
-{
-#if false
-    [MethodImpl(MethodImplOptions.NoInlining)]
-            public static /*extern*/ ref Q AccessBox2(MyBox<Q> q) => throw new NotImplementedException("exn");
-#else
-    [UnsafeAccessor(UnsafeAccessorKind.Field, Name="_value")]
-    public static extern ref Q AccessBox2(MyBox<Q> q);
-#endif
-}
-
-public class SimpleHelper
-{
-    [UnsafeAccessor(UnsafeAccessorKind.Field, Name="_value")]
-    public static extern ref decimal AccessSimpleBox(SimpleBox b);
-}
-
-#else
-
-public class MyService<T>
-{
-        public MyService() {}
-
-        private static string Explain(T arg) => arg.ToString() + " : " + typeof(T).ToString(); //$"{arg} : {typeof(T)}";
-}
-
-public class Program
-{
-        public static void Main()
+        private static void Main(string[] args)
         {
-                new Program().Runner<string>("abcd");
+            bool isMono = typeof(object).Assembly.GetType("Mono.RuntimeStructs") != null;
+            Console.WriteLine($"Hello World {(isMono ? "from Mono!" : "from CoreCLR!")}");
+            Console.WriteLine(typeof(object).Assembly.FullName);
+            Console.WriteLine(System.Reflection.Assembly.GetEntryAssembly ());
+            Console.WriteLine(System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription);
         }
-
-        [MethodImpl(MethodImplOptions.NoInlining)]
-        public void Runner<Q>(Q x)
-        {
-                Console.WriteLine (AccessHelper<Q>.CallExplain(default, x));
-        }
-
-}
-
-public static class AccessHelper<W>
-{
-        [UnsafeAccessor(UnsafeAccessorKind.StaticMethod, Name="Explain")]
-        public static extern string CallExplain(MyService<W> target, W arg);
-
+    }
 }
-
-#endif