fix: lazy load command object types to reduce unnecessary allocations

Author: natemcmaster

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 [Unreleased changes](https://github.com/natemcmaster/CommandLineUtils/compare/v2.5.0...HEAD):
 
+## [v2.5.1](https://github.com/natemcmaster/CommandLineUtils/compare/v2.5.0...v2.5.1)
+
+* Fix [#320] - lazy load command object types to reduce unnecessary allocations
+
 ## [v2.5.0](https://github.com/natemcmaster/CommandLineUtils/compare/v2.4.4...v2.5.0)
 
 * Fix [#92] by [@kbilsted] - Show enum names in help text for Options and Arguments stored as enum

Directory.Build.props

@@ -46,7 +46,7 @@
   </PropertyGroup>
 
    <PropertyGroup>
-    <VersionPrefix>2.5.0</VersionPrefix>
+    <VersionPrefix>2.5.1</VersionPrefix>
     <VersionSuffix>rc</VersionSuffix>
     <IncludePreReleaseLabelInPackageVersion Condition="'$(IsStableBuild)' != 'true'">true</IncludePreReleaseLabelInPackageVersion>
     <BuildNumber Condition=" '$(BuildNumber)' == '' ">$(BUILD_NUMBER)</BuildNumber>

src/CommandLineUtils/CommandLineApplication{T}.cs

@@ -115,10 +115,9 @@ public Func<TModel> ModelFactory
         }
 
         /// <inheritdoc />
+        // TODO remove in 3.0. This doesn't do anything anymore.
         protected override void HandleParseResult(ParseResult parseResult)
         {
-            (this as IModelAccessor).GetModel();
-
             base.HandleParseResult(parseResult);
         }
 
@@ -127,7 +126,7 @@ protected override void HandleParseResult(ParseResult parseResult)
         /// <inheritdoc />
         public override void Dispose()
         {
-            if (Model is IDisposable dt)
+            if (_lazy.IsValueCreated && Model is IDisposable dt)
             {
                 dt.Dispose();
             }

src/CommandLineUtils/releasenotes.props

@@ -7,6 +7,9 @@ Features and bug fixes:
 * @Alxandr: Add support for private base type options
 * @AndreGleichner: Update generated help to display [command] first then [options]
 * @daveMueller: Fix generated help to display the help options correctly
+
+Patch 2.5.1:
+* Lazy load command object types to reduce unnecessary allocations
     </PackageReleaseNotes>
     <PackageReleaseNotes Condition="$(VersionPrefix.StartsWith('2.4.'))">
 Features and bug fixes by some awesome contributors:

test/CommandLineUtils.Tests/CommandLineApplicationExecutorTests.cs

@@ -293,7 +293,7 @@ public void OnExecute()
         public void DisposesSubCommands()
         {
             var ex = Assert.Throws<InvalidOperationException>(
-                () => CommandLineApplication.Execute<ParentCommand>(NullConsole.Singleton, "sub"));
+                () => CommandLineApplication.Execute<ParentCommand>(NullConsole.Singleton, "disposable"));
             Assert.Equal("Hello", ex.Message);
         }
 
@@ -312,8 +312,12 @@ public void Dispose()
         [Command("sub")]
         private class Subcommand
         {
+            public DisposableParentCommand Parent { get; }
+            
             public void OnExecute()
-            { }
+            {
+                Assert.NotNull(Parent);
+            }
         }
 
         [Fact]

test/CommandLineUtils.Tests/CommandLineApplicationOfTTests.cs

@@ -1,8 +1,10 @@
 // Copyright (c) Nate McMaster.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using Xunit;
 using Xunit.Abstractions;
+using Xunit.Sdk;
 
 namespace McMaster.Extensions.CommandLineUtils.Tests
 {
@@ -75,14 +77,51 @@ public void ThrowsForArgumentsWithoutMatchingAttribute()
         private class TestClass
         {
             public TestClass(string _) { }
+
+            public void OnExecute() { }
         }
 
         [Fact]
         public void ThrowsForNoParameterlessConstructor()
         {
-            var app = new CommandLineApplication<TestClass>();
+            var app = new CommandLineApplication<TestClass>(new TestConsole(_output));
+            app.Conventions.UseOnExecuteMethodFromModel();
             var exception = Assert.Throws<MissingParameterlessConstructorException>(() => app.Execute());
             Assert.Equal(typeof(TestClass), exception.Type);
         }
+
+        [Subcommand(typeof(SimpleCommand))]
+        class ThrowsInCtorClass
+        {
+            public ThrowsInCtorClass()
+            {
+                throw new XunitException("Parent comand object should not be initialized.\n" + Environment.StackTrace);
+            }
+
+            public void OnExecute() { }
+        }
+
+        [Fact]
+        public void ItDoesNotInitalizeClassUnlessNecessary()
+        {
+            using var app = new CommandLineApplication<ThrowsInCtorClass>(new TestConsole(_output));
+            app.Conventions.UseDefaultConventions();
+            var parseResult = app.Parse();
+            Assert.NotNull(parseResult);
+            Assert.Same(app, parseResult.SelectedCommand);
+        }
+
+        class SimpleCommand
+        {
+            public int OnExecute() => 2;
+        }
+
+        [Fact]
+        public void ItDoesNotInitalizeParentClassUnlessNecessary()
+        {
+            using var app = new CommandLineApplication<ThrowsInCtorClass>(new TestConsole(_output));
+            app.Conventions.UseDefaultConventions();
+            Assert.Equal(2, app.Execute("simple"));
+        }
     }
 }