Make VisualStudio run a command to generate C# code

Question

I'm trying to do something extremely simple, yet despite hours of scouring the Internet and desperately typing in every tiny example fragment I can find, I literally cannot make VS do what I want. Seriously frustrated here!

This is what I want:

When I do a build, I want VS to find every *.fubar file in the project.
For each *.fubar file, I want VS to execute fubar.exe with the input file as argument.
I want VS to compile the resulting *.cs files as usual.

I am damn-well convinced it must be possible to achieve this trivially simple task. I just need to figure out how.

So that's the problem. Let me explain what I've researched so far.

It seems that you can write a VS extension by implementing some COM interface. But that requires you to edit the Registry to tell VS where the plugin is. Obviously that's completely unacceptable; I should not have to reconfigure the OS just to run a command-line tool!

It appears that MSBuild is supposed to be this ultra-configurable build management tool where you can define an arbitrary set of build steps and their interdependencies. It seems like it should be trivial to add an extra task before the build C# compilation step that runs fubar.exe to generate the source code. And yet, after hours of trying, I cannot get a single C# file to appear.

Some documents talk about special pre-build and post-build steps. But it seems silly to need a special hook when the number and order of build steps is supposed to be arbitrary to begin with. Regardless, I tried it, and it still didn't work.

To be clear: Playing around with the project file makes VS display the item properties slightly differently, and doesn't make the build fail. But it also doesn't ever make any C# files appear. (At least, I can't find them anywhere on the disk. I can't tell if my tool is actually being run or not — I suspect "not".)

Can anybody tell me how to make this trivial, trivial thing work? There must be a way!

It is not a trivial, trivial thing. What you are talking about can be implemented as a "custom tool", which (as you say) requires registration. It can be implemented by making significant changes to the csproj, but that is very very ugly. In XRE projects (vNext), there is a drop-in folder based precompilation step, but I have yet to see any good examples about how to set it up (I would like to see them though, as I do a lot of metaprogramming) — Marc Gravell
– Marc Gravell, Commented Mar 19, 2015 at 14:55
You can extend MsBuild with a custom target that triggers pre-compile and extend the "Compile" item group on the fly with your generated .cs files (put them on /obj/confiuration using a fubar.g.cs extension). Canyou share what you've tried? — jessehouwing
– jessehouwing, Commented Mar 19, 2015 at 14:56
you can probably do it as a prebuild step. But I agree with the previous comment it is not simple. — Philip Stuyck
– Philip Stuyck, Commented Mar 19, 2015 at 14:56

jessehouwing · Accepted Answer · 2015-03-19 17:55:40Z

I agree that T4 may be a prettier solution, but the below MsBuild code works.

You can create a custom targets file that does the calling, I created one that simply copies files, but the process should be similar for invoking your executable.

Make sure you set your FuBar files to BuildAction "Fubars". The Build action has been defined in the targets file using the "AvailableItemName" property.

You may need to extend the below script with a couple of Conditions and Exists checks to make sure it runs when needed. I called it convert.targets and places it in the project directory.

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

  <!-- Ensure Visual Studio puts the FuBars item in the Build Action dropdown -->
  <ItemGroup>
    <AvailableItemName Include="FuBars" />
  </ItemGroup>

  <!-- Execute action on all items matching FuBar (only if output is missing or input has changed) -->
  <Target Name="GenerateCodeFubar" Inputs="@(Fubars)" Outputs="$(MSBuildProjectDirectory)/obj/$(Configuration)/Fubars/%(Fubars.Identity).g.cs" >
    <MakeDir Directories="$(MSBuildProjectDirectory)/obj/$(Configuration)/Fubars/%(Fubars.RelativeDir)" />

    <Exec Command="cmd /c copy &quot;%(FuBars.FullPath)&quot; &quot;$(MSBuildProjectDirectory)/obj/$(Configuration)/Fubars/%(FuBars.Identity).g.cs&quot;"/>
  </Target>

  <!-- Pick up generated code in the Compile group. Separated from the execute action so that the previous action only runs when files have changes -->
  <Target Name="IncludeCodeFubarInCompile">
    <ItemGroup>
      <GeneratedFubars Include="$(MSBuildProjectDirectory)/obj/$(Configuration)/Fubars/%(FuBars.Identity).g.cs"/>
    </ItemGroup>

    <CreateItem Include="%(GeneratedFubars.FullPath)">
      <Output TaskParameter="Include" ItemName="Compile" />
    </CreateItem>
  </Target>

  <!-- Clean up for Rebuild or Clean -->
  <Target Name="DeleteCodeFubar">
   <RemoveDir Directories="$(MSBuildProjectDirectory)/obj/$(Configuration)/Fubars/" />
     <Delete Files="$(MSBuildProjectDirectory)/obj/$(Configuration)/fubars/**/*.g.cs" />
  </Target>

    <!-- Instruct MsBuild when to call target on Build-->
    <PropertyGroup>
        <BuildDependsOn>
            GenerateCodeFubar;
            IncludeCodeFubarInCompile;
            $(BuildDependsOn);
        </BuildDependsOn>
    </PropertyGroup>

    <!-- Instruct MsBuild when to call target on Clean-->    
    <PropertyGroup>
        <CleanDependsOn>
            DeleteCodeFubar;
            $(CleanDependsOn);
        </CleanDependsOn>
    </PropertyGroup>
</Project>

Include it in your .csproj after the import the last targets file:

  </ItemGroup>
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />

  <!-- IMPORT HERE -->
  <Import Project="convert.targets" />
  <!-- END: IMPORT HERE -->

  <!-- To modify your build process, add your task inside one of the targets below and uncomment it.
       Other similar extension points exist, see Microsoft.Common.targets.
  <Target Name="BeforeBuild">
  </Target>
  <Target Name="AfterBuild">
  </Target>
  -->
</Project>

You may have to tell Visual Studio to turn off the Host Compiler, as Visual Studio caches the contents of the <Compile> group for performance. Though a quick test shows this may not be needed.

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
  <!-- The first property group should not have any condition on it -->
  <PropertyGroup> 

    <!-- Include below item in the first PropertyGroup item:
    <UseHostCompilerIfAvailable>FALSE</UseHostCompilerIfAvailable>
  </PropertyGroup>

Now, when I see it, it ain't so hard either :o). It may not be as trivial as a single copy action though.
I just spent many, many hours trying to figure out why this doesn't work. You know why? My antivirus product is blocking the command! AAARGH!
My God, it might have actually been working before... [Although I doubt it.] Whatever; I can see it generating the files. Now I just need to get the AV to stop sandboxing it...

Sam Axe · Accepted Answer · 2015-03-19 15:19:40Z

-1

This is extremely easy.

In your project properties select the Build Events tab and enter a correct Pre-build event command line.

Without knowing what footer.exe is nor its command line args, I can't give you any specific help for that app. But there is a "Macros" button on the pre-build event dialog that can help you with various substitution variables.

Additionally, VS comes with the T4 templating system which might be a better fit than whatever footer.exe is.

answered Mar 19, 2015 at 15:19

Sam Axe

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3 Comments

MathematicalOrchid Over a year ago

I spent an hour or so reading about T4. But it seems to generate one output file per T4 file, not one output file per input file.

MathematicalOrchid Over a year ago

It is unclear to me how I make VS run fubar.exe multiple times (once with each input file as the command argument).

jessehouwing Over a year ago

It is not extremely easy, as Visual Studio will not know of the output of foobar.exe unless you either really integrate in MsBuild (see other answer) or change the project file on the fly (which will make Visual Studio balk).

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