luaInterface2 and luaSQL

[Terry Bayne <trbayne@...>]

Good evening,

For those of you who have been following along you will remember I had 
issues getting luaInterface (version 2) to work with the luaForWindows 
version of luaSQL in Visual Studio .NET 2008 - for my particular usage 
this was critical.

I've hit upon a solution and thought I would pass along the technique in 
case anyone else is trying to utilize one or more of the modules with 
luaInterface 2:

The solution involves building the module into the luaDLL that gets 
built as part of the luaInterface build.  Sounds complicated but it 
really wasn't.  The hardest part was reworking the luaSQL code to handle 
the odbc32 SQLWCHAR type rather than the SQLCHAR type.  Here is what I did:

In the file "luainterface2\lua-5.1.2\src\linit.c"

// Added the call to open the luaSQL module - this will cause the module 
to be loaded automatically

static const luaL_Reg lualibs[] = {
  {"", luaopen_base},
  {LUA_LOADLIBNAME, luaopen_package},
  {LUA_TABLIBNAME, luaopen_table},
  {LUA_IOLIBNAME, luaopen_io},
  {LUA_OSLIBNAME, luaopen_os},
  {LUA_STRLIBNAME, luaopen_string},
  {LUA_MATHLIBNAME, luaopen_math},
  {LUA_DBLIBNAME, luaopen_debug},
  {LUA_LUASQL, luaopen_luasql_odbc},
  {NULL, NULL}
};

// Added the prototype and supporting entries in 
"luainterface2\lua-5.1.2\src\lualib.h"

#ifndef LUASQL_API
    #define LUASQL_API
#endif
#define LUA_LUASQL "luasql"
LUASQL_API int luaopen_luasql_odbc (lua_State *L);

Created a directory called "Modules" in "luainterface2\lua-5.1.2\src"

Copied the relevant source code files to the 
luainterface2\lua-5.1.2\src\Modules directory:

luainterface2\lua-5.1.2\src\Modules
    ls_odbc.c
    luasql.c
    luasql.h

Added the following two lines to 
"luainterface2\lua-5.1.2\src\luaglue.cpp" - this causes the luaSQL code 
to be included and compiled

#include "Modules/luasql.c"
#include "Modules/ls_odbc.c"

Edited ls_odbc.c and modified the code to use SQLWCHAR in the right 
places and to convert from SQLWCHAR
to char where needed.

Added odbc32.lib to the list of libraries to be linked with.

Then I rebuilt the luaInteface project, creating the two DLLs in 
luainterface2\Built:

lua51.dll
LuaInterface.dll

I then added those DLLs as references in my C# Windows Application 
project.  This allowed me to use Lua as so:

    private Lua pLuaVM = null;
    pLuaVM = new Lua();

Just as described in the LuaInterface documentation.  In lua code I can 
access luaSQL like this - note that "require luasql" isnt needed - the 
module is built into the Lua51.dll and automatically loaded:

    sql_env, Msg = luasql.odbc()
    connection, Msg = sqlEnv:connect(odbcName,userName, password)

Feel free to ping me with any questions.  The modified source to luaSQL 
is pretty specific to my needs and wouldn't likely do anyone else much 
good.  On the other hand, the technique I used to get it working could 
be useful to anyone trying to integrate using luaInteface and .NET with 
various lua modules.  Is this a clean and generic solution?  No it is 
not.  Does it work?  Like a charm.

Have a great evening
Terry