From: Paul Brannan <paul@...>
Date: 2001-12-28T23:54:45+09:00
Subject: [ruby-talk:29532] Re: GC and values in extensions

On Fri, Dec 28, 2001 at 11:32:02PM +0900, ts wrote:
> >>>>> "P" == Paul Brannan <paul@atdesk.com> writes:
> 
> P> I've heard this same response before, but I'm not sure quite what you
> P> mean.  How does the GC know how long the object "lives"?
> 
>  Look at rb_gc() and stack_end

Hmm, interesting.  So if I do something like this:

  VALUE foo(VALUE self) {
    VALUE x = rb_str_new2("foo");
    long y = (long)x; /* Assume x and y now have the same bit pattern */
    x = Qnil;
    ...
    return Qnil;
  }

then the newly allocated string will not be freed until foo returns?  Or
if I happen to store an integer that happens to look like a pointer to
the heap, then it is possible that some object that has no more
references may not actually get garbage-collected?  So there is no way
to depend on objects being garbage-collected, even if there are no more
references?

This also sounds a little inefficient to me (though it makes things
convenient for extension writers).  Is it?

Paul