Stack handling and exiting a comp via next() - ATTN Jon this needs your input

Jon, in the 1.3x series, you changed the way the request object manages 
the stack so we no longer use Perl's push and pop to add/remove items from 
the stack. Instead, we manually manipulate track the current stack depth.

AFAICT, this was done to work around stack corruption when a component 
exits via next(). Unfortunately, the side effect was to introduce a pretty 
nasty leak, because what ended up happening is that stack frames were 
never being removed from the stack, we just changed changed the value of 
the "top of the stack" variable internally.

In 1.34, I introduced a change to pop the stack so that the frame (and 
objects it references) actually get destroyed when the user expects. I 
consider this a pretty serious bug, more serious than stack corruption 
because of a bogus next.

Unfortunately, it seems like this popping introduced more bugs. The 
existing code is really complicated, because it is in effect a 
re-implementation of what Perl does internally for array handling.

When I revert the code back to just using Perl's push and pop, as we did 
through 1.28, the tests pass except for the "exit via next" test.

Personally, I think that this is fine. The problem with next or last is 
unfortunate, but Perl at least spits out a warning when you do it, so the 
user gets some clue as to what's going on. It's not intractable to find 
such bugs, and IMO it's not worth impossible gyrations to work around 
this, especially when fundamentally the problem is with Perl itself. Using 
next or last outside of loops should just be a no-op.

Anyway, I'd like to go ahead and revert the code that tries to manually 
manage the stack and just use push and pop, like we used to, and then 
release 1.3401 (or 1.35).

The real rub in all this is that I haven't been able to come up with a 
nice isolated test of what I'm seeing in my app with 1.34 (a screwed up 
stack where one of the frames is undef, for example). I'll keep trying to 
come up with such a test.


-dave

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