Re: Garbage collection and controlled types (was Re: Java knocks the heck outa ...)

[ncohen@watson.ibm.com (Norman H. Cohen)]

In article <EACHUS.96Mar18144400@spectre.mitre.org>,
eachus@spectre.mitre.org (Robert I. Eachus) writes: 

|>    Yes, it is more work, but you probably have no idea how USEFUL it
|> is to be able to back up the state of the computation.  This is
|> especially true if what you are trying to debug is a rare exception or
|> the like.

It is especially true if your program has just mistakenly launched an
ICBM!

But seriously, folks: This approach is in principle possible with certain
well-contained applications such as compilers.  It cannot apply to
programs that alter the state of the world outside the program
(especially in ways that are not easily reversible, e.g. by launching a
missile or deleting a file); or that query aspects of that state that are
changing independently of the program (e.g. the time of day or the
contents of a shared data base).  And in a multitask program it would be
necessary to replay not only the actions of a particular task, but all
the task scheduling events that determined how tasks were interleaved.

--
Norman H. Cohen    ncohen@watson.ibm.com