Creating Resource-Only Assemblies

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Working on some localization stuff, I’ve come across the need for resource assemblies to be created from .resx files in a post-build step - I have the .resx files, but I don’t want them at all to be attached to my application. I just want them built into a tiny hierarchy of resource-only assemblies so I can get a ResourceManager on them and have string lookup behave as expected.

I also find that sometimes I need to recompile .resx without recompiling the whole app and I forget the command-lines to do all that.

The overall process:

  1. Convert your .resx files to .resources files using resgen.exe.
  2. Link your .resources files into assembly format using al.exe.

Again, what I’m showing here assumes that the assemblies you’re compiling are resource-only - which is to say, there is no code to compile and you’re not linking resources into existing assemblies.

For a culture-neutral (default) resource-only assembly, you’ll use:

resgen.exe "Path\To\Culture\Neutral\Strings.resx" "Path\To\Output\Folder\Strings.resources"
al.exe /embed:"Path\To\Output\Folder\Strings.resources" /out:"Path\To\Bin\Strings.dll"

The first command line generates the .resources file from .resx and puts it in an output folder. It doesn’t really matter where the output folder is; it’s a temporary place to store the .resources file before it gets compiled into an assembly. The second line links the .resource file into assembly format and puts it in your application’s “bin” folder, where you can start to consume it.

For a culture-specific resource-only assembly, you add culture-specific parameters and output locations into the mix:

resgen.exe "Path\To\Culture\Specific\" "Path\To\Output\Folder\"
al.exe /c:es /embed:"Path\To\Output\Folder\" /out:"Path\To\Bin\es\Strings.resources.dll"

In the above example, we’re compiling general Spanish resources, as noted by the “es” in there. If we wanted Spanish specific to Mexico, we’d use “es-MX” as the culture. The key differences to note:

  • In the .resx and .resources files, we specify the culture before the extension. While this isn’t mandatory, it is standard convention and helps you keep your source .resx and output .resources files organized.
  • In the al.exe command line, we add the /c: parameter to specify what culture we’re linking for and we put the output assembly in a folder under “bin” that is named after the culture we’re linking for. We also add “resources” just before the .dll extension so the ResourceManager knows it’s a resource assembly. (You don’t do that for culture-neutral resources, so you didn’t see that before.)

This is pretty easy to do in a Visual Studio project post-build step, too:

"$(VS80COMNTOOLS)..\..\SDK\v2.0\Bin\resgen.exe" "$(ProjectDir)\Strings.resx" "$(TargetDir)Strings.resources"
"$(WINDIR)\Microsoft.NET\Framework\v2.0.50727\al.exe" /embed:"$(TargetDir)Strings.resources" /out:"$(TargetDir)Strings.dll"
"$(VS80COMNTOOLS)..\..\SDK\v2.0\Bin\resgen.exe" "$(ProjectDir)\" "$(TargetDir)"
"$(WINDIR)\Microsoft.NET\Framework\v2.0.50727\al.exe" /c:es /embed:"$(TargetDir)" /out:"$(TargetDir)es\Strings.resources.dll"

Note we had to specify some paths to resgen.exe and al.exe because the post-build step isn’t run as part of a Visual Studio 2008 command prompt environment.

Obviously, change your paths and parameters as needed, but the above compiles and links a neutral and a generic Spanish “Strings” assembly in a post-build step.