InteropDotNet

The library allows you to work with native libraries. Standard approach with the DllImport attribute may be inconvenient if you want to build AnyCPU assembly with MS.NET/Mono support. The InteropRuntimeImplementer class can generate implementation of interface with target signatures of native methods.

For example, let's create a native library (NativeLib) with the function int sum(int a, int b) { return a + b; } and build it in four configuration (Windows/Unix, x86/x64):

x86/NativeLib.dll
x86/libNativeLib.so
x64/NativeLib.dll
x64/libNativeLib.so

Now we can write the following code:

public interface INative
{
    [RuntimeDllImport("NativeLib", CallingConvention = CallingConvention.Cdecl, EntryPoint = "sum")]
    int Sum(int a, int b);
}

class Program
{
    static void Main()
    {
        var native = InteropRuntimeImplementer.CreateInstance<INative>();
        Console.WriteLine("2 + 3 = " + native.Sum(2, 3));
    }
}

In the program, we declared interface INative with signatures of the target native methods. Each signature should be marked with the RuntimeDllImport attribute with name of a native library and other options. The instance of InteropRuntimeImplementer helped us to create instance of the INative interface on the fly. The implementation of the sum method call corresponding native method from library that correspond to current architecture and OS. The InteropRuntimeImplementer generates the following code:

namespace InteropRuntimeImplementer.NativeInstance
{
  [UnmanagedFunctionPointer(CallingConvention.Cdecl, BestFitMapping = false, CharSet = (CharSet) 0, SetLastError = false, ThrowOnUnmappableChar = false)]
  [StructLayout(LayoutKind.Auto, CharSet = CharSet.Auto)]
  public delegate int SumDelegate(int a, int b);

  public class NativeImplementation : INative
  {
    private SumDelegate SumField;

    public NativeImplementation(LibraryLoader loader)
    {
      IntPtr dllHandle = loader.LoadLibrary("NativeLib", (string) null);
      this.SumField = (SumDelegate) Marshal.GetDelegateForFunctionPointer(loader.GetProcAddress(dllHandle, "sum"), typeof (SumDelegate));
    }

    public int Sum(int a, int b)
    {
      return this.SumField(a, b);
    }
  }
} 

As a result, we received a single .NET cross-platform AnyCPU-program with calls of native methods because of the LibraryLoader class loaded handles for specific user environment.

NuGet

You can install the library via NuGet: https://www.nuget.org/packages/InteropDotNet/