Source generators for command handlers

System.CommandLine.sln

@@ -58,6 +58,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "System.CommandLine.Hosting.
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HostingPlayground", "samples\HostingPlayground\HostingPlayground.csproj", "{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.CommandLine.CommandGenerator", "src\System.CommandLine.CommandGenerator\System.CommandLine.CommandGenerator.csproj", "{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -236,6 +238,18 @@ Global
 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Release|x64.Build.0 = Release|Any CPU
 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Release|x86.ActiveCfg = Release|Any CPU
 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Release|x86.Build.0 = Release|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|x64.Build.0 = Debug|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|x86.Build.0 = Debug|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|x64.ActiveCfg = Release|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|x64.Build.0 = Release|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|x86.ActiveCfg = Release|Any CPU
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -255,6 +269,7 @@ Global
 		{644C4B4A-4A32-4307-9F71-C3BF901FFB66} = {E5B1EC71-0FC4-4FAA-9C65-32D5016FBC45}
 		{39483140-BC26-4CAD-BBAE-3DC76C2F16CF} = {E5B1EC71-0FC4-4FAA-9C65-32D5016FBC45}
 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906} = {6749FB3E-39DE-4321-A39E-525278E9408D}
+		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C} = {E5B1EC71-0FC4-4FAA-9C65-32D5016FBC45}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {5C159F93-800B-49E7-9905-EE09F8B8434A}

eng/source-build-patches/0001-Exclude-dotnet-suggest-from-source-build.patch

@@ -6,15 +6,14 @@ Subject: [PATCH 1/3] Exclude dotnet-suggest from source-build.
 This is not used by any downstream repos in source-build and adds a
 bunch of prebuilts, so we can leave this out for now.
 ---
- System.CommandLine.sln                        | 134 ------------------
- .../dotnet-suggest.csproj                     |   1 +
- 2 files changed, 1 insertion(+), 134 deletions(-)
+ System.CommandLine.sln | 156 +------------------------------------------------
+ 1 file changed, 3 insertions(+), 153 deletions(-)
 
 diff --git a/System.CommandLine.sln b/System.CommandLine.sln
-index ec97010..102aefe 100644
+index 7441d0ef..1519e16c 100644
 --- a/System.CommandLine.sln
 +++ b/System.CommandLine.sln
-@@ -30,31 +30,14 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{E5B1EC71-0FC
+@@ -30,35 +30,15 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{E5B1EC71-0FC
  EndProject
  Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.CommandLine", "src\System.CommandLine\System.CommandLine.csproj", "{0BE8E56E-7580-4526-BE24-D304E1779724}"
  EndProject
@@ -43,10 +42,15 @@ index ec97010..102aefe 100644
  Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.CommandLine.Hosting", "src\System.CommandLine.Hosting\System.CommandLine.Hosting.csproj", "{644C4B4A-4A32-4307-9F71-C3BF901FFB66}"
  EndProject
 -Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "System.CommandLine.Hosting.Tests", "src\System.CommandLine.Hosting.Tests\System.CommandLine.Hosting.Tests.csproj", "{39483140-BC26-4CAD-BBAE-3DC76C2F16CF}"
+-EndProject
+-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HostingPlayground", "samples\HostingPlayground\HostingPlayground.csproj", "{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}"
+-EndProject
+-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.CommandLine.CommandGenerator", "src\System.CommandLine.CommandGenerator\System.CommandLine.CommandGenerator.csproj", "{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}"
++Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "HostingPlayground", "samples\HostingPlayground\HostingPlayground.csproj", "{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}"
  EndProject
- Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "HostingPlayground", "samples\HostingPlayground\HostingPlayground.csproj", "{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}"
- EndProject
-@@ -78,30 +61,6 @@ Global
+ Global
+ 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+@@ -82,30 +62,6 @@ Global
  		{0BE8E56E-7580-4526-BE24-D304E1779724}.Release|x64.Build.0 = Release|Any CPU
  		{0BE8E56E-7580-4526-BE24-D304E1779724}.Release|x86.ActiveCfg = Release|Any CPU
  		{0BE8E56E-7580-4526-BE24-D304E1779724}.Release|x86.Build.0 = Release|Any CPU
@@ -77,7 +81,7 @@ index ec97010..102aefe 100644
  		{EEC30462-078F-45EB-AA70-12E3170CD51E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
  		{EEC30462-078F-45EB-AA70-12E3170CD51E}.Debug|Any CPU.Build.0 = Debug|Any CPU
  		{EEC30462-078F-45EB-AA70-12E3170CD51E}.Debug|x64.ActiveCfg = Debug|Any CPU
-@@ -114,54 +73,6 @@ Global
+@@ -118,54 +74,6 @@ Global
  		{EEC30462-078F-45EB-AA70-12E3170CD51E}.Release|x64.Build.0 = Release|Any CPU
  		{EEC30462-078F-45EB-AA70-12E3170CD51E}.Release|x86.ActiveCfg = Release|Any CPU
  		{EEC30462-078F-45EB-AA70-12E3170CD51E}.Release|x86.Build.0 = Release|Any CPU
@@ -132,7 +136,7 @@ index ec97010..102aefe 100644
  		{27E3BFFC-4412-4E4C-A656-B9D35B8A0F3E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
  		{27E3BFFC-4412-4E4C-A656-B9D35B8A0F3E}.Debug|Any CPU.Build.0 = Debug|Any CPU
  		{27E3BFFC-4412-4E4C-A656-B9D35B8A0F3E}.Debug|x64.ActiveCfg = Debug|Any CPU
-@@ -174,30 +85,6 @@ Global
+@@ -178,30 +86,6 @@ Global
  		{27E3BFFC-4412-4E4C-A656-B9D35B8A0F3E}.Release|x64.Build.0 = Release|Any CPU
  		{27E3BFFC-4412-4E4C-A656-B9D35B8A0F3E}.Release|x86.ActiveCfg = Release|Any CPU
  		{27E3BFFC-4412-4E4C-A656-B9D35B8A0F3E}.Release|x86.Build.0 = Release|Any CPU
@@ -163,7 +167,7 @@ index ec97010..102aefe 100644
  		{644C4B4A-4A32-4307-9F71-C3BF901FFB66}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
  		{644C4B4A-4A32-4307-9F71-C3BF901FFB66}.Debug|Any CPU.Build.0 = Debug|Any CPU
  		{644C4B4A-4A32-4307-9F71-C3BF901FFB66}.Debug|x64.ActiveCfg = Debug|Any CPU
-@@ -210,48 +97,27 @@ Global
+@@ -214,18 +98,6 @@ Global
  		{644C4B4A-4A32-4307-9F71-C3BF901FFB66}.Release|x64.Build.0 = Release|Any CPU
  		{644C4B4A-4A32-4307-9F71-C3BF901FFB66}.Release|x86.ActiveCfg = Release|Any CPU
  		{644C4B4A-4A32-4307-9F71-C3BF901FFB66}.Release|x86.Build.0 = Release|Any CPU
@@ -182,15 +186,22 @@ index ec97010..102aefe 100644
  		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
  		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Debug|Any CPU.Build.0 = Debug|Any CPU
  		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Debug|x64.ActiveCfg = Debug|Any CPU
- 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Debug|x64.Build.0 = Debug|Any CPU
- 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Debug|x86.ActiveCfg = Debug|Any CPU
- 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Debug|x86.Build.0 = Debug|Any CPU
- 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Release|Any CPU.ActiveCfg = Release|Any CPU
- 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Release|Any CPU.Build.0 = Release|Any CPU
- 		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Release|x64.ActiveCfg = Release|Any CPU
+@@ -238,38 +110,16 @@ Global
  		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Release|x64.Build.0 = Release|Any CPU
  		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Release|x86.ActiveCfg = Release|Any CPU
  		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906}.Release|x86.Build.0 = Release|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|Any CPU.Build.0 = Debug|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|x64.ActiveCfg = Debug|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|x64.Build.0 = Debug|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|x86.ActiveCfg = Debug|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Debug|x86.Build.0 = Debug|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|Any CPU.ActiveCfg = Release|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|Any CPU.Build.0 = Release|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|x64.ActiveCfg = Release|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|x64.Build.0 = Release|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|x86.ActiveCfg = Release|Any CPU
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C}.Release|x86.Build.0 = Release|Any CPU
  	EndGlobalSection
  	GlobalSection(SolutionProperties) = preSolution
  		HideSolutionNode = FALSE
@@ -210,20 +221,7 @@ index ec97010..102aefe 100644
  		{644C4B4A-4A32-4307-9F71-C3BF901FFB66} = {E5B1EC71-0FC4-4FAA-9C65-32D5016FBC45}
 -		{39483140-BC26-4CAD-BBAE-3DC76C2F16CF} = {E5B1EC71-0FC4-4FAA-9C65-32D5016FBC45}
  		{0BF6958D-9EE3-4623-B3D6-4DA77EAC1906} = {6749FB3E-39DE-4321-A39E-525278E9408D}
+-		{B0D00128-E41B-4648-9D22-9B91F8F6BF0C} = {E5B1EC71-0FC4-4FAA-9C65-32D5016FBC45}
  	EndGlobalSection
  	GlobalSection(ExtensibilityGlobals) = postSolution
-diff --git a/src/System.CommandLine.Suggest/dotnet-suggest.csproj b/src/System.CommandLine.Suggest/dotnet-suggest.csproj
-index f529484..ef9c3bb 100644
---- a/src/System.CommandLine.Suggest/dotnet-suggest.csproj
-+++ b/src/System.CommandLine.Suggest/dotnet-suggest.csproj
-@@ -13,6 +13,7 @@
-     <DotnetSuggestBuildNumber Condition="'$(VersionSuffixDateStamp)' != ''">.$(VersionSuffixDateStamp).$(VersionSuffixBuildOfTheDay)</DotnetSuggestBuildNumber>
-     <VersionPrefix>1.1$(DotnetSuggestBuildNumber)</VersionPrefix>
-     <VersionSuffix></VersionSuffix>
-+    <ExcludeFromSourceBuild>true</ExcludeFromSourceBuild>
-   </PropertyGroup>
-
-   <PropertyGroup>
--- 
-2.18.0
-
+ 		SolutionGuid = {5C159F93-800B-49E7-9905-EE09F8B8434A}

eng/source-build-patches/0003-Update-to-netcoreapp3.1-to-avoid-prebuilts.patch

@@ -8,15 +8,30 @@ rest of source-build: runtime and roslyn.
 
 Includes a code fix for ref nullability with the new framework.
 ---
- .../System.CommandLine.DragonFruit.csproj                  | 2 +-
- .../System.CommandLine.Hosting.csproj                      | 2 +-
- .../System.CommandLine.Rendering.csproj                    | 2 +-
- src/System.CommandLine/Binding/BindingContext.cs           | 2 +-
- src/System.CommandLine/System.CommandLine.csproj           | 7 +------
- 5 files changed, 5 insertions(+), 10 deletions(-)
+ .../System.CommandLine.CommandGenerator.csproj                     | 4 ++--
+ .../System.CommandLine.DragonFruit.csproj                          | 2 +-
+ src/System.CommandLine.Hosting/System.CommandLine.Hosting.csproj   | 2 +-
+ .../System.CommandLine.Rendering.csproj                            | 2 +-
+ src/System.CommandLine/Binding/BindingContext.cs                   | 2 +-
+ src/System.CommandLine/System.CommandLine.csproj                   | 7 +------
+ 6 files changed, 7 insertions(+), 12 deletions(-)
 
+diff --git a/src/System.CommandLine.CommandGenerator/System.CommandLine.CommandGenerator.csproj b/src/System.CommandLine.CommandGenerator/System.CommandLine.CommandGenerator.csproj
+index d419906e..8644194a 100644
+--- a/src/System.CommandLine.CommandGenerator/System.CommandLine.CommandGenerator.csproj
++++ b/src/System.CommandLine.CommandGenerator/System.CommandLine.CommandGenerator.csproj
+@@ -1,7 +1,7 @@
+-<Project Sdk="Microsoft.NET.Sdk">
++<Project Sdk="Microsoft.NET.Sdk">
+
+   <PropertyGroup>
+-    <TargetFramework>netstandard2.0</TargetFramework>
++    <TargetFramework>net5.0</TargetFramework>
+     <Nullable>enable</Nullable>
+     <LangVersion>9.0</LangVersion>
+     <IsPackable>true</IsPackable>
 diff --git a/src/System.CommandLine.DragonFruit/System.CommandLine.DragonFruit.csproj b/src/System.CommandLine.DragonFruit/System.CommandLine.DragonFruit.csproj
-index b3a542fd..06167997 100644
+index b3a542fd..0e49d818 100644
 --- a/src/System.CommandLine.DragonFruit/System.CommandLine.DragonFruit.csproj
 +++ b/src/System.CommandLine.DragonFruit/System.CommandLine.DragonFruit.csproj
 @@ -1,7 +1,7 @@
@@ -29,7 +44,7 @@ index b3a542fd..06167997 100644
      </Description>
    </PropertyGroup>
 diff --git a/src/System.CommandLine.Hosting/System.CommandLine.Hosting.csproj b/src/System.CommandLine.Hosting/System.CommandLine.Hosting.csproj
-index 1d00cff2..7342c1c5 100644
+index bed1b893..913edb72 100644
 --- a/src/System.CommandLine.Hosting/System.CommandLine.Hosting.csproj
 +++ b/src/System.CommandLine.Hosting/System.CommandLine.Hosting.csproj
 @@ -2,7 +2,7 @@
@@ -42,7 +57,7 @@ index 1d00cff2..7342c1c5 100644
      <Description>This package provides support for using System.CommandLine with Microsoft.Extensions.Hosting.</Description>
    </PropertyGroup>
 diff --git a/src/System.CommandLine.Rendering/System.CommandLine.Rendering.csproj b/src/System.CommandLine.Rendering/System.CommandLine.Rendering.csproj
-index d552286e..84026ebe 100644
+index bd5ce1d7..762481d9 100644
 --- a/src/System.CommandLine.Rendering/System.CommandLine.Rendering.csproj
 +++ b/src/System.CommandLine.Rendering/System.CommandLine.Rendering.csproj
 @@ -2,7 +2,7 @@
@@ -55,10 +70,10 @@ index d552286e..84026ebe 100644
      <Description>This package provides support for structured command line output rendering. Write code once that renders correctly in multiple output modes, including System.Console, virtual terminal (using ANSI escape sequences), and plain text.
      </Description>
 diff --git a/src/System.CommandLine/Binding/BindingContext.cs b/src/System.CommandLine/Binding/BindingContext.cs
-index b942ba6a..bbb83891 100644
+index a80a4172..305a95ab 100644
 --- a/src/System.CommandLine/Binding/BindingContext.cs
 +++ b/src/System.CommandLine/Binding/BindingContext.cs
-@@ -55,7 +55,7 @@ namespace System.CommandLine.Binding
+@@ -56,7 +56,7 @@ namespace System.CommandLine.Binding
 
          public ModelBinder GetModelBinder(IValueDescriptor valueDescriptor)
          {
@@ -68,7 +83,7 @@ index b942ba6a..bbb83891 100644
                  return binder;
              }
 diff --git a/src/System.CommandLine/System.CommandLine.csproj b/src/System.CommandLine/System.CommandLine.csproj
-index aaa2c4a3..5e875a73 100644
+index 125e9c78..3a10c14d 100644
 --- a/src/System.CommandLine/System.CommandLine.csproj
 +++ b/src/System.CommandLine/System.CommandLine.csproj
 @@ -3,7 +3,7 @@
@@ -79,8 +94,8 @@ index aaa2c4a3..5e875a73 100644
 +    <TargetFramework>net5.0</TargetFramework>
      <LangVersion>9</LangVersion>
      <Nullable>enable</Nullable>
-     <Description>This package includes a powerful command line parser and other tools for building command line applications, including:
-@@ -18,9 +18,4 @@
+
+@@ -26,11 +26,6 @@
      <Compile Include="..\System.Diagnostics.CodeAnalysis.cs" Link="System.Diagnostics.CodeAnalysis.cs" />
    </ItemGroup>
 
@@ -90,6 +105,5 @@ index aaa2c4a3..5e875a73 100644
 -  </ItemGroup>
 -
    <ItemGroup>
--- 
-2.25.2
-
+     <Compile Update="Properties\Resources.Designer.cs">
+       <DesignTime>True</DesignTime>

global.json

@@ -1,6 +1,6 @@
 {
   "tools": {
-    "dotnet": "5.0.100",
+    "dotnet": "5.0.300",
     "vs": {
       "version": "16.8"
     },

src/System.CommandLine.CommandGenerator/CommandHandlerGenerator.cs

@@ -0,0 +1,122 @@
+using Microsoft.CodeAnalysis;
+using System.Linq;
+using System.Text;
+
+namespace System.CommandLine.CommandGenerator
+{
+    [Generator]
+    public class CommandHandlerGenerator : ISourceGenerator
+    {
+        private const string ICommandHandlerType = "System.CommandLine.Invocation.ICommandHandler";
+
+        public void Execute(GeneratorExecutionContext context)
+        {
+            SyntaxReceiver rx = (SyntaxReceiver)context.SyntaxContextReceiver!;
+
+            StringBuilder builder = new();
+            builder.AppendLine(@"
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+#nullable disable
+using System.CommandLine.Binding;
+using System.Reflection;
+using System.Threading.Tasks;
+
+namespace System.CommandLine.Invocation
+{
+    public static partial class CommandHandlerGeneratorExtensions_Generated
+    {
+");
+            int count = 1;
+            foreach (var invocation in rx.Invocations)
+            {
+                var methodParamters = invocation.Parameters
+                    .Select(x => x.GetMethodParameter())
+                    .Where(x => !string.IsNullOrWhiteSpace(x.Name))
+                    .ToList();
+
+                builder.AppendLine(@$"public static {ICommandHandlerType} Generate<{string.Join(", ", Enumerable.Range(1, invocation.NumberOfGenerericParameters).Select(x => $"Unused{x}"))}>(this CommandHandlerGenerator handler,");
+                builder.AppendLine($"{invocation.DelegateType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)} method");
+                if (methodParamters.Count > 0)
+                {
+                    builder.AppendLine(",");
+                    builder.AppendLine(string.Join($", ", methodParamters.Select(x => $"{x.Type} {x.Name}")));
+                }
+                builder.AppendLine(")");
+                builder.AppendLine("{");
+                builder.Append($"return new GeneratedHandler_{count}(method");
+                if (methodParamters.Count > 0)
+                {
+                    builder.Append(", ");
+                    builder.Append(string.Join(", ", methodParamters.Select(x => x.Name)));
+                }
+                builder.AppendLine(");");
+
+                builder.AppendLine("}");
+
+
+                //TODO: fully qualify type names
+                builder.AppendLine($@"
+        private class GeneratedHandler_{count} : {ICommandHandlerType}
+        {{
+            public GeneratedHandler_{count}({invocation.DelegateType} method");
+
+                if (methodParamters.Count > 0)
+                {
+                    builder.AppendLine(",");
+                    builder.AppendLine(string.Join($", ", methodParamters.Select(x => $"{x.Type} {x.Name}")));
+                }
+
+                builder.AppendLine($@")
+            {{
+                Method = method;");
+                foreach (var propertyAssignment in invocation.Parameters
+                    .Select(x => x.GetPropertyAssignment())
+                    .Where(x => !string.IsNullOrWhiteSpace(x)))
+                {
+                    builder.AppendLine(propertyAssignment);
+                }
+                builder.AppendLine($@"
+            }}
+
+            public {invocation.DelegateType} Method {{ get; }}");
+
+                foreach (var propertyDeclaration in invocation.Parameters
+                    .Select(x => x.GetPropertyDeclaration())
+                    .Where(x => !string.IsNullOrWhiteSpace(x)))
+                {
+                    builder.AppendLine(propertyDeclaration);
+                }
+
+                builder.AppendLine($@"
+            public async Task<int> InvokeAsync(InvocationContext context)
+            {{");
+                builder.AppendLine(invocation.InvokeContents());
+                builder.AppendLine($@"
+            }}
+        }}");
+                count++;
+            }
+
+            builder.AppendLine(@"
+    }
+}
+#nullable restore");
+
+            context.AddSource("CommandHandlerGeneratorExtensions_Generated.g.cs", builder.ToString());
+        }
+
+        public void Initialize(GeneratorInitializationContext context)
+        {
+#if DEBUG
+            if (!System.Diagnostics.Debugger.IsAttached)
+            {
+                //System.Diagnostics.Debugger.Launch();
+            }
+#endif
+
+            context.RegisterForSyntaxNotifications(() => new SyntaxReceiver());
+        }
+    }
+}