Hosting CLR in Delphi with/without JCL – example

Here’s another option.

That’s the C# Code. And even if you do not want to use my unmanaged exports, it would still
explain how to use mscoree (the CLR hosting stuff) without going through IDispatch (IDispatch is pretty slow).

using System;
using System.Collections.Generic;
using System.Text;
using RGiesecke.DllExport;
using System.Runtime.InteropServices;

namespace DelphiNET
{

   [ComVisible(true)]
   [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
   [Guid("ACEEED92-1A35-43fd-8FD8-9BA0F2D7AC31")]
   public interface IDotNetAdder
   {
      int Add3(int left);
   }

   [ComVisible(true)]
   [ClassInterface(ClassInterfaceType.None)]
   public class DotNetAdder : DelphiNET.IDotNetAdder
   {
      public int Add3(int left)
      {
         return left + 3;
      }
   }

   internal static class UnmanagedExports
   {
      [DllExport("createdotnetadder", CallingConvention = System.Runtime.InteropServices.CallingConvention.StdCall)]
      static void CreateDotNetAdderInstance([MarshalAs(UnmanagedType.Interface)]out IDotNetAdder instance)
      {
         instance = new DotNetAdder();
      }
   }
}

This is the Delphi interface declaration:

type
  IDotNetAdder = interface
  ['{ACEEED92-1A35-43fd-8FD8-9BA0F2D7AC31}']
    function Add3(left : Integer) : Integer; safecall;
  end;

If you use unmanaged exports, you can do it like so:

procedure CreateDotNetAdder(out instance :  IDotNetAdder); stdcall;
  external 'DelphiNET' name 'createdotnetadder';

var
  adder : IDotNetAdder;
begin
  try
   CreateDotNetAdder(adder);
   Writeln('4 + 3 = ', adder.Add3(4));
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.

When I adapt Lars’ sample, it would look like so:

var
  Host: TJclClrHost;
  Obj: IDotNetAdder;
begin
  try
    Host := TJclClrHost.Create;
    Host.Start();
    WriteLn('CLRVersion = ' + Host.CorVersion);

    Obj := Host.DefaultAppDomain
               .CreateInstance('DelphiNET', 
                               'DelphiNET.DotNetAdder')
               .UnWrap() as IDotNetAdder;
    WriteLn('2 + 3 = ', Obj.Add3(2));

    Host.Stop();
  except
    on E: Exception do
      Writeln(E.Classname, ': ', E.Message);
  end;
end.

In this case you could remove the “UnmanagedExports” class from the C# code, of course.