Function tryfuncTM

src/Chain/libraries/glua/ldo.cpp:336–351

** Check whether __call metafield of 'func' is a function. If so, put ** it in stack below original 'func' so that 'luaD_precall' can call ** it. Raise an error if __call metafield is not a function. */

** it. Raise an error if __call metafield is not a function.
*/
static void tryfuncTM(lua_State *L, StkId func) {
    const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
    StkId p;
    if (!ttisfunction(tm))
    {
        global_glua_chain_api->throw_exception(L, THINKYOUNG_API_LVM_ERROR, "Can't find __call method");
        luaG_typeerror(L, func, "call");
    }
    if (L->force_stopping)
        return;
    /* Open a hole inside the stack at 'func' */
    for (p = L->top; p > func; p--)
        setobjs2s(L, p, p - 1);
    L->top++;  /* slot ensured by caller */
    setobj2s(L, func, tm);  /* tag method is the new function to be called */
}