dotnet · jonsequitur · Nov 11, 2022 · Nov 4, 2022
diff --git a/...ty.Tests/ApiCompatibilityApprovalTests.System_CommandLine_api_is_not_changed.approved.txt b/...ty.Tests/ApiCompatibilityApprovalTests.System_CommandLine_api_is_not_changed.approved.txt
@@ -353,15 +353,13 @@ System.CommandLine.Help
     public System.Boolean Equals(TwoColumnHelpRow other)
     public System.Int32 GetHashCode()
 System.CommandLine.Invocation
-  public interface IInvocationResult
-    public System.Void Apply(InvocationContext context)
   public class InvocationContext, System.IDisposable
     .ctor(System.CommandLine.ParseResult parseResult, System.CommandLine.IConsole console = null, System.Threading.CancellationToken cancellationToken = null)
     public System.CommandLine.Binding.BindingContext BindingContext { get; }
     public System.CommandLine.IConsole Console { get; set; }
     public System.Int32 ExitCode { get; set; }
     public System.CommandLine.Help.HelpBuilder HelpBuilder { get; }
-    public IInvocationResult InvocationResult { get; set; }
+    public System.Action<InvocationContext> InvocationResult { get; set; }
     public System.CommandLine.LocalizationResources LocalizationResources { get; }
     public System.CommandLine.Parsing.Parser Parser { get; }
     public System.CommandLine.ParseResult ParseResult { get; set; }

diff --git a/src/System.CommandLine.NamingConventionBinder.Tests/ModelBindingCommandHandlerTests.cs b/src/System.CommandLine.NamingConventionBinder.Tests/ModelBindingCommandHandlerTests.cs
@@ -46,9 +46,7 @@ public async Task Unspecified_option_arguments_with_no_default_value_are_bound_t
 
         await handler.InvokeAsync(invocationContext);
 
-        var boundValue = ((BoundValueCapturer)invocationContext.InvocationResult).BoundValue;
-
-        boundValue.Should().Be(expectedValue);
+        BoundValueCapturer.GetBoundValue(invocationContext).Should().Be(expectedValue);
     }
 
     [Theory]
@@ -125,7 +123,7 @@ public async Task Handler_method_receives_option_arguments_bound_to_the_specifie
 
         await handler.InvokeAsync(invocationContext);
 
-        var boundValue = ((BoundValueCapturer)invocationContext.InvocationResult).BoundValue;
+        var boundValue = BoundValueCapturer.GetBoundValue(invocationContext);
 
         boundValue.Should().BeAssignableTo(testCase.ParameterType);
 
@@ -188,7 +186,7 @@ public async Task Handler_method_receives_command_arguments_bound_to_the_specifi
 
         await handler.InvokeAsync(invocationContext);
 
-        var boundValue = ((BoundValueCapturer)invocationContext.InvocationResult).BoundValue;
+        var boundValue = BoundValueCapturer.GetBoundValue(invocationContext);
 
         boundValue.Should().BeOfType(testCase.ParameterType);
 
@@ -240,7 +238,7 @@ public async Task Handler_method_receives_command_arguments_explicitly_bound_to_
 
         await handler.InvokeAsync(invocationContext);
 
-        var boundValue = ((BoundValueCapturer)invocationContext.InvocationResult).BoundValue;
+        var boundValue = BoundValueCapturer.GetBoundValue(invocationContext);
 
         boundValue.Should().BeOfType(testCase.ParameterType);
 
@@ -293,7 +291,7 @@ public async Task Handler_method_receive_option_arguments_explicitly_bound_to_th
 
         await handler.InvokeAsync(invocationContext);
 
-        var boundValue = ((BoundValueCapturer)invocationContext.InvocationResult).BoundValue;
+        var boundValue = BoundValueCapturer.GetBoundValue(invocationContext);
 
         boundValue.Should().BeOfType(testCase.ParameterType);
 
@@ -323,26 +321,32 @@ public async Task Unexpected_return_types_result_in_exit_code_0_if_no_exception_
 
     private static void CaptureMethod<T>(T value, InvocationContext invocationContext)
     {
-        invocationContext.InvocationResult = new BoundValueCapturer(value);
+        BoundValueCapturer.Capture(value, invocationContext);
+
+        invocationContext.InvocationResult = ctx => BoundValueCapturer.Apply(ctx);
     }
 
     private static Action<T, InvocationContext> CaptureDelegate<T>()
-    {
-        return (value, invocationContext) => invocationContext.InvocationResult = new BoundValueCapturer(value);
-    }
+        => (value, invocationContext) =>
+        {
+            BoundValueCapturer.Capture(value, invocationContext);
 
-    private class BoundValueCapturer : IInvocationResult
+            invocationContext.InvocationResult = ctx => BoundValueCapturer.Apply(ctx);
+        };
+
+    private static class BoundValueCapturer
     {
-        public BoundValueCapturer(object boundValue)
+        private static readonly Dictionary<InvocationContext, object> _boundValues = new ();
+
+        public static void Apply(InvocationContext context)
         {
-            BoundValue = boundValue;
         }
 
-        public object BoundValue { get; }
+        public static void Capture(object value, InvocationContext invocationContext)
+            => _boundValues.Add(invocationContext, value);
 
-        public void Apply(InvocationContext context)
-        {
-        }
+        public static object GetBoundValue(InvocationContext context)
+            => _boundValues.TryGetValue(context, out var value) ? value : null;
     }
 
     internal static readonly BindingTestSet BindingCases = new()

diff --git a/src/System.CommandLine/Builder/CommandLineBuilderExtensions.cs b/src/System.CommandLine/Builder/CommandLineBuilderExtensions.cs
@@ -500,7 +500,7 @@ public static CommandLineBuilder UseParseDirective(
             {
                 if (context.ParseResult.Directives.Contains("parse"))
                 {
-                    context.InvocationResult = new ParseDirectiveResult(errorExitCode);
+                    context.InvocationResult = ctx => ParseDirectiveResult.Apply(ctx, errorExitCode);
                 }
                 else
                 {
@@ -525,7 +525,7 @@ public static CommandLineBuilder UseParseErrorReporting(
             {
                 if (context.ParseResult.Errors.Count > 0)
                 {
-                    context.InvocationResult = new ParseErrorResult(errorExitCode);
+                    context.InvocationResult = ctx => ParseErrorResult.Apply(ctx, errorExitCode);
                 }
                 else
                 {
@@ -560,7 +560,7 @@ public static CommandLineBuilder UseSuggestDirective(
                         position = context.ParseResult.CommandLineText?.Length ?? 0;
                     }
 
-                    context.InvocationResult = new SuggestDirectiveResult(position);
+                    context.InvocationResult = ctx => SuggestDirectiveResult.Apply(ctx, position);
                 }
                 else
                 {
@@ -649,7 +649,7 @@ public static CommandLineBuilder UseVersionOption(
                 {
                     if (context.ParseResult.Errors.Any(e => e.SymbolResult?.Symbol is VersionOption))
                     {
-                        context.InvocationResult = new ParseErrorResult(null);
+                        context.InvocationResult = static ctx => ParseErrorResult.Apply(ctx, null);
                     }
                     else
                     {
@@ -690,7 +690,7 @@ public static CommandLineBuilder UseVersionOption(
                 {
                     if (context.ParseResult.Errors.Any(e => e.SymbolResult?.Symbol is VersionOption))
                     {
-                        context.InvocationResult = new ParseErrorResult(null);
+                        context.InvocationResult = static ctx => ParseErrorResult.Apply(ctx, null);
                     }
                     else
                     {
@@ -712,7 +712,7 @@ private static bool ShowHelp(
         {
             if (context.ParseResult.FindResultFor(helpOption) is { })
             {
-                context.InvocationResult = new HelpResult();
+                context.InvocationResult = HelpResult.Apply;
                 return true;
             }
 

diff --git a/src/System.CommandLine/Help/HelpResult.cs b/src/System.CommandLine/Help/HelpResult.cs
@@ -6,10 +6,9 @@
 
 namespace System.CommandLine.Help
 {
-    internal class HelpResult : IInvocationResult
+    internal static class HelpResult
     {
-        /// <inheritdoc />
-        public void Apply(InvocationContext context)
+        internal static void Apply(InvocationContext context)
         {
             var output = context.Console.Out.CreateTextWriter();
 

diff --git a/src/System.CommandLine/Invocation/IInvocationResult.cs b/src/System.CommandLine/Invocation/IInvocationResult.cs
diff --git a/src/System.CommandLine/Invocation/InvocationContext.cs b/src/System.CommandLine/Invocation/InvocationContext.cs
@@ -105,7 +105,7 @@ public IConsole Console
         /// The result of the current invocation.
         /// </summary>
         /// <remarks>As the <see cref="InvocationContext"/> is passed through the invocation pipeline to the <see cref="ICommandHandler"/> associated with the invoked command, only the last value of this property will be the one applied.</remarks>
-        public IInvocationResult? InvocationResult { get; set; }
+        public Action<InvocationContext>? InvocationResult { get; set; }
 
         /// <summary>
         /// Gets a cancellation token that can be used to check if cancellation has been requested.

diff --git a/src/System.CommandLine/Invocation/InvocationPipeline.cs b/src/System.CommandLine/Invocation/InvocationPipeline.cs
@@ -93,7 +93,7 @@ private static InvocationMiddleware BuildInvocationChain(InvocationContext conte
 
         private static int GetExitCode(InvocationContext context)
         {
-            context.InvocationResult?.Apply(context);
+            context.InvocationResult?.Invoke(context);
 
             return context.ExitCode;
         }

diff --git a/src/System.CommandLine/Invocation/ParseDirectiveResult.cs b/src/System.CommandLine/Invocation/ParseDirectiveResult.cs
@@ -6,22 +6,15 @@
 
 namespace System.CommandLine.Invocation
 {
-    internal class ParseDirectiveResult : IInvocationResult
+    internal static class ParseDirectiveResult
     {
-        private readonly int? _errorExitCode;
-
-        public ParseDirectiveResult(int? errorExitCode)
-        {
-            _errorExitCode = errorExitCode;
-        }
-
-        public void Apply(InvocationContext context)
+        internal static void Apply(InvocationContext context, int? errorExitCode)
         {
             var parseResult = context.ParseResult;
             context.Console.Out.WriteLine(parseResult.Diagram());
             context.ExitCode = parseResult.Errors.Count == 0
                                      ? 0
-                                     : _errorExitCode ?? 1;
+                                     : errorExitCode ?? 1;
         }
     }
 }
diff --git a/src/System.CommandLine/Invocation/ParseErrorResult.cs b/src/System.CommandLine/Invocation/ParseErrorResult.cs
@@ -6,17 +6,9 @@
 
 namespace System.CommandLine.Invocation
 {
-    internal class ParseErrorResult : IInvocationResult
+    internal static class ParseErrorResult
     {
-        private readonly int? _errorExitCode;
-
-        public ParseErrorResult(int? errorExitCode)
-        {
-            _errorExitCode = errorExitCode;
-        }
-
-        /// <inheritdoc />
-        public void Apply(InvocationContext context)
+        internal static void Apply(InvocationContext context, int? errorExitCode)
         {
             context.Console.ResetTerminalForegroundColor();
             context.Console.SetTerminalForegroundRed();
@@ -28,11 +20,11 @@ public void Apply(InvocationContext context)
 
             context.Console.Error.WriteLine();
 
-            context.ExitCode = _errorExitCode ?? 1;
+            context.ExitCode = errorExitCode ?? 1;
 
             context.Console.ResetTerminalForegroundColor();
 
-            new HelpResult().Apply(context);
+            HelpResult.Apply(context);
         }
     }
 }
diff --git a/src/System.CommandLine/Invocation/SuggestDirectiveResult.cs b/src/System.CommandLine/Invocation/SuggestDirectiveResult.cs
@@ -7,22 +7,15 @@
 
 namespace System.CommandLine.Invocation
 {
-    internal class SuggestDirectiveResult : IInvocationResult
+    internal static class SuggestDirectiveResult
     {
-        private readonly int _position;
-
-        public SuggestDirectiveResult(int position)
-        {
-            _position = position;
-        }
-
-        public void Apply(InvocationContext context)
+        internal static void Apply(InvocationContext context, int position)
         {
             var commandLineToComplete = context.ParseResult.Tokens.LastOrDefault(t => t.Type != TokenType.Directive)?.Value ?? "";
 
             var completionParseResult = context.Parser.Parse(commandLineToComplete);
 
-            var completions = completionParseResult.GetCompletions(_position);
+            var completions = completionParseResult.GetCompletions(position);
 
             context.Console.Out.WriteLine(
                 string.Join(