Question

I know the prototype and arguements this function takes

id class_createInstance(Class cls, size_t extraBytes)

but where can i find its implementation?Is it just malloc or…

Answer 1

It’s more that just malloc as the object needs to be initialsed etc. This the GNUstep implementation:

id class_createInstance(Class cls, size_t extraBytes)
{
    CHECK_ARG(cls);
    if (sizeof(id) == 4)
    {
        if (cls == SmallObjectClasses[0])
        {
            return (id)1;
        }
    }
    else
    {
        for (int i=0 ; i<4 ; i++)
        {
            if (cls == SmallObjectClasses[i])
            {
                return (id)(uintptr_t)((i<<1)+1);
            }
        }
    }

    if (Nil == cls) { return nil; }
    id obj = gc->allocate_class(cls, extraBytes);
    obj->isa = cls;
    call_cxx_construct(obj);
    return obj;
}