initialize_copy

VALUE
rb_obj_init_copy(VALUE obj, VALUE orig)
{
    if (obj == orig) return obj;
    rb_check_frozen(obj);
    if (TYPE(obj) != TYPE(orig) || rb_obj_class(obj) != rb_obj_class(orig)) {
        rb_raise(rb_eTypeError, "initialize_copy should take same class object");
    }
    return obj;
}