But the interpreter isn't cleaning up the object, it's setting the
reference to undef. The object is still around (and accessible
by other means).
I like your recreational-swim analogy, but I'm still trying to
figure out how the behavior I'm seeing is consistent with the
specified operation of the garbage collector. The Camel book says that
objects are always destroyed in a separate pass before ordinary
references (3rd ed. page 331), and maybe that's a clue, but there's
still a problem:
When the interpreter is ready to exit, presumably "everything"
goes out of scope. At that point, there are no references left to my
$::index object. So it should be garbage collected pretty early. But
it's not and, worse, an object reference it's holding is set to undef
at some apparently arbritrary moment. I've been very careful to avoid
circular references, so there *is* a sensible destruction order for
these objects. But if references disappear without provocation, then
that order can't be maintained.