From: William Djaja Tjokroaminata <billtj@...>
Date: 2002-09-25T23:43:01+09:00
Subject: Re: Object-Oriented struct Model in C

Paul Brannan <pbrannan@atdesk.com> wrote:
> You don't really need references to all the inner the objects on the
> stack; you could have a reference to an object that holds references to
> all your inner objects.

But at any level, if that object that holds references to the inner
objects was not created using Data_Wrap_Struct(), there is no way for it
to mark the inner objects, is there?

> An array of VALUES allocated with ALLOCA would work, as long as it is
> aligned properly on the stack.  This uses more stack space than a Ruby
> Array, but is cheaper to construct.

Very good point, Paul.

> Also note that if you have a structure like this:


>                +-A
>           Top--|
>                +-B--+-C
>                     |
>                     +-D

> Then you only need to keep references C and D on the stack while
> registering B; you only need to keep references to A and B while
> registering Top (since C and D are already referred to by B).

Actually, what is the meaning of "registering B"?  Is it
rb_gc_register_address()?  I am assuming here only the Top object is
created using Data_Wrap_Struct().  (If we use rb_gc_register_address(),
doesn't it mean that we don't need any mark function?  We then just need
to rb_gc_unregister_address() when the C destructor is called.)

Regards,

Bill