How to call managed c++ dll functions in lua cpp module

Question

Description:

All my functions are defined in C# dll project.Then I wrap the c# functions in a cpp library project,Now I want to write a lua module using c++ and call the wrapper function.

Question:

How to call the wrapper functions in lua cpp module? Please give me some suggestions, Thanks!

Codes:

libutilscore Project(C# DLL)

 namespace libutilscore
 {
     public static class SharpFTP
     {
         public static string ShowHello()
         {
             return "Hello From C Sharp.";
         }
     }
  }

ManagedDll Project(C++ DLL)

ManagedDll.h

#pragma once
#ifdef MANAGEDDLL_EXPORTS
#define MANAGEDDLL_API __declspec(dllexport)
#else
#define MANAGEDDLL_API __declspec(dllimport)
#endif

MANAGEDDLL_API const char *CPP_ShowHello();

ManagedDll.cpp

#include "ManagedDll.h"
#include <string>
using namespace System;
using namespace std;
using namespace libutilscore;

namespace ManagedDll
{
   public ref class CS_FTP
   {
       public:
          static string CS_ShowHello()
          {
              String ^ message = libutilscore::SharpFTP::ShowHello();
              string result = "";
              MarshallString(message, result);
              return result;
          }
       private:
          static void MarshallString(String ^csstr, string &stdstr)
          {
              using namespace Runtime::InteropServices;
              const char *chars = (const char*)(Marshal::StringToHGlobalAnsi(csstr)).ToPointer();
              stdstr = chars;
              Marshal::FreeHGlobal(IntPtr((void *)chars));
          }

          static void MarshallWstring(String ^csstr, string &wstr)
          {
              using namespace Runtime::InteropServices;
              const char *wchars = (const wchar_t*)(Marshal::StringToHGlobalAnsi(csstr)).ToPointer();
              wstr = wchars;
              Marshal::FreeHGlobal(IntPtr((void *)wchars));
          }
    };
}

MANAGEDDLL_API string CPP_ShowHello() 
{
    return ManagedDll::CS_FTP::CS_ShowHello();
}

libutils Project(Lua CPP Module)

libutils.h

#pragma once

#ifdef LIBUTILS_EXPORTS
    #define LIBUTILS_API __declspec(dllexport)
#else
    #define LIBUTILD_API __declspec(dllimport)
#endif // LIBUTILS_EXPORTS

libutils.cpp

#include "libutils.h"
#include "lua.hpp"

LIBUTILS_API int showHello(lua_State *luaEnv)
{
    const char *msg = "";
    // TODO Call DLL function
    // msg = CPP_ShowHello().c_str();
    lua_pushstring(luaEnv, msg);
    return 1;
}

static const luaL_Reg libutils_funcs[] = {
    {"showHello", showHello},
    {"NULL", NULL}
};

LIBUTILS_API int luaopen_libutils(lua_State *luaEnv)
{
    luaL_newlib(luaEnv, libutils_funcs);
    return 1;
}

score 1 · Answer 1 · answered May 11 '18 at 14:25

One option MAY be to make your "Lua CPP Module" a mixed-mode DLL. I have answered previously on this topic, so read my instructions there on how to do it: VC++ Calling a function of /clr project from a function of non /clr project within a solution The short answer is that you can compile specific parts of a DLL to use the CLR without making the whole thing that way, and then call between them.

Basically, once you've figured out how to call a mixed-mode DLL from PURE C++ code, then this problem is very similar. I don't know about restrictions on LUA C++ modules, though I would presume if they can load/call other DLLs, then you're fine.

For extra fun, then figure out how to pass information all the way back and forth. And calling pure C++ from C#/.NET. Or callbacks to/from each. That gets really fun quickly.

How to call managed c++ dll functions in lua cpp module

1 Answers1