davea at ieee.org
Sat Jul 4 12:09:34 EDT 2009
Steven D'Aprano wrote:
> On Sat, 04 Jul 2009 09:58:39 -0400, Dave Angel wrote:
>> Read his suggested approach more carefully. He's not "undoing"
>> anything. He's rolling back to the save-point, and then stepping
>> forward to the desired spot. Except for influences outside his control
>> (eg. file system operations), this approach has to work.
> Is that anything like saying "Except for all the diseases this drug won't
> cure, it cures everything"?
Yeah, pretty close. That's the problem with speaking in concepts,
rather than something concrete.
Somebody else brought up VM, but that has two meanings these days. The
sense I took it (with regard to save-point) was a program like VMWare,
where it virtualizes the entire machine. So any program that deals only
with the local machine will fit that approach. And yes, I know there
are subtleties beyond networks and virtual networks, like time. When
you roll the VM back, the time magically stays current. But for a
program that deals only with its own process, that tends to just look
like some other process suddenly hogged the CPU.
Now, if the snapshot is a feature of the Python VM, that's another
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