Re: Re: How do I manipulate C++ vectors of C structs in Lua?

["Zé Pedro" <zarroba@...>]

Thanks for the reply, but I'm not sure if that's what I want. I already do something like that when translating C++ classes to lua, but two dimensional arrays, I'm having dificulties seeing how to do it. Taking your example would it be something like:

// export two dimensional arrays to Lua
static int class_to_lua_table(lua_State* L)
{
   string[][] matrix = getMatrix(name);

   lua_newtable(L);

   int table_stack_pos = lua_gettop(L);

   for (int i=0; i<matrix.size; i++)
      lua_pushnumber(L, matrix.i);                         //??????
      lua_setfield(L, table_stack_pos, i);      //??????
      for (int j=0; i<matrix[i].size; j++)
         lua_pushnumber(L, matrix.i.j);           //??????
         lua_setfield(L, table_stack_pos, matrix[i][j]);

   return 1;
}

It doesn't make much sense to me....

Thanks,
Jose Pedro Tavares

On 11/10/06, Ken Smith <kgsmith@gmail.com> wrote:

On 11/10/06, Zé Pedro <zarroba@gmail.com> wrote:
> Hi,
> I have a similar problem, instead of a Vector a have a matrix of strings
> that I have in C that I want to send to Lua for manipulation in there. I'm
> aware that I can do it with metatables but I just don't know how. Imagine I
> have the following function:
[snip]

I don't even bother with metatables.  I just convert C/C++ structures
and classes to nested tables.  I set up a function that looks
something like this and its inverse if I must get the table back into
the C/C++ struct/class.

// global
static SomeClass c;

// export this to Lua
static int class_to_lua_table(lua_State* L)
{
   lua_newtable(L);

   int table_stack_pos = lua_gettop(L);

   lua_pushnumber(L, c.val1);
   lua_setfield(L, table_stack_pos, "val1");

   lua_pushnumber(L, c.val2);
   lua_setfield(L, table_stack_pos, "val2");

   subclass_to_lua_table(L, c.sub);  // implementation implied
   lua_setfield(L, table_stack_pos, "sub");

   return 1;
}

Then, once you've registered that function to Lua, you can do this, for example.

c = class_to_lua_table()

print(c.val1, c.val2, c.sub.data1, c.sub.data2)

I find this to be the simplest solution but I basically just use C/C++
to bootstrap into Lua and implement all the logic in Lua so I either
don't need or can easily wrap the methods in the classes.  YMMV.

  Ken Smith

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