Function trymt

extlibs/lua/src/lstrlib.c:276–283

static void trymt (lua_State *L, const char *mtname) {
  lua_settop(L, 2);  /* back to the original arguments */
  if (lua_type(L, 2) == LUA_TSTRING || !luaL_getmetafield(L, 2, mtname))
    luaL_error(L, "attempt to %s a '%s' with a '%s'", mtname + 2,
                  luaL_typename(L, -2), luaL_typename(L, -1));
  lua_insert(L, -3);  /* put metamethod before arguments */
  lua_call(L, 2, 1);  /* call metamethod */
}


static int arith (lua_State *L, int op, const char *mtname) {