views:

241

answers:

1

I notice that in the generated SWIG wrappers for a given set of classes, SWIG keeps a list of C-string representations of all the parent classes from which that class inherits. (char ** base_names). I know there is a function

swig_type(some_variable)

that will return a string representation of a given variable's data type. Is there also a function that will return a table of the parent classes as strings? If not, is there an easy way to write this function? I'm not at all familiar with the inner workings of SWIG.

Thanks!

+2  A: 

Something like this should work (not tested, since I don't use SWIG with Lua):

// insert into runtime section
// this is the C function that iterates over the base_names array 
// (I'm assuming that the array is terminated with a NULL)
%runtime %{
    /* lua callable function to get the userdata's type */
    SWIGRUNTIME int SWIG_Lua_basenames(lua_State* L)
    {
      swig_lua_userdata* usr;
      swig_lua_class* clss = NULL;
      int i = 0;
      if (lua_isuserdata(L,1))
      {
        usr=(swig_lua_userdata*)lua_touserdata(L,1);  /* get data */
        if (usr && usr->type && usr->type->clientdata) {
          // fetch the swig_lua_class struct, it contains the base_names
          clss = (swig_lua_class*)usr->type->clientdata;
        }
      }
      /* create a new table with all class base names in it
         note that I create it even if clss is NULL, that way
         an empty table -should- be returned
       */          
      lua_newtable(L);
      while(clss && clss->base_names[i]) {
         lua_pushnumber(L, i+1); /* lua tables are 1-indexed */
         lua_pushstring(L, clss->base_names[i]);
         lua_rawset(L, -3);
         i++;
      }
      return 1;
    }
%}
%init %{
  /* this goes into the user init function, register our new function with
     Lua runtime
   */
  SWIG_Lua_add_function(L,"swig_base_names",SWIG_Lua_basenames);
%}
ASk
Initial testing shows that your code works like a champ!Thanks so much, that's a great help!
Zack