The Moth

A question came up in the ng, and my reply included the statement "CF 1.0 does not support multi-module assemblies [...]". So I thought I'd check to see if that changed in CF2.0. The short answer is "yes, they are supported"! If you are on the CF team, please let me know why you are offering this feature. What was the driver for it? Anyway, read on to see an example of multifile assemblies in CF 2.0.

If you don't know about multi module/file assemblies, I suggest you search the web for definitions, as I am not going to describe the principles (the feature is available in the .NET full framework today). In a small nutshell, you compile code in modules (.netmodule extension and nothing to do with VB's module) that you can link to from an existing assembly. (Alternatively, using al.exe you create an assembly that holds the manifest only and references the real code in one or more netmodules).

So here is how to do it with CF 2.0

1. Create a ProgramMixed.cs file with this code in it

namespace MixedLanguages {
  static class Program {
    [System.STAThread]
    static void Main() {
      System.Windows.Forms.Application.Run(
                             new MixedLanguages.Form1());
    }
  }
}

2. Create a Form1Mixed.vb file with this code in it

Namespace MixedLanguages
  Public Class Form1
    Inherits System.Windows.Forms.Form

    Public Sub New()
      Me.Text = "Run from Csharp code"
      Me.MinimizeBox = False
    End Sub
  End Class
End Namespace

3. In the command line type the following (assuming you have all the PATH variables set and you are pointing to the right directories):


vbc /netcf /noconfig /nostdlib /r:"E:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\CompactFramework\WindowsCE\mscorlib.dll","E:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\CompactFramework\WindowsCE\System.dll","E:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\CompactFramework\WindowsCE\System.Windows.Forms.dll" /t:module Form1Mixed.vb

You should get a Form1Mixed.netmodule file created (note that /sdkpath crashes with Beta 1).

4. Also type this:


csc /noconfig /nostdlib /r:"E:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\CompactFramework\WindowsCE\mscorlib.dll","E:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\CompactFramework\WindowsCE\System.dll","E:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\CompactFramework\WindowsCE\System.Windows.Forms.dll" /addmodule:Form1Mixed.netmodule ProgramMixed.cs


You should have a ProgramMixed.exe created.

In both successful command line compiles, the output looks something like this:

Microsoft (R) Visual Basic .NET Compiler version 8.0.40607.16
for Microsoft (R) .NET Framework version 2.0.40607.16
Copyright (C) Microsoft Corporation 1987-2003. All rights reserved.

5. You now have 2 files. Copy them to your device or the emulator and run the exe (in fact, since they are retargetable, you can run the exe on the PC as well). That's it!

So, apart from the ability to mix languages without having to create separate dlls, what is the advantage of multifile assemblies? I am not sure. Maybe the search you did earlier has given you the answer, in which case let me know. There are some benefits listed here (and an example).

I would be much more excited if we could actually statically link the netmodules into a single file. This becomes reality in VS2005 on the desktop, but only for C++.

UPDATE: Turns out we can merge the netmodule into a single exe file.