[PEAK] Heads-up: new Trellis algorithm arriving in SVN soon

Peter Damoc pdamoc at gmail.com
Wed Nov 28 04:40:50 EST 2007

Hi Phillip,
What other peak libraries need to be updated for trellis to work?

I just checked out the SVN, tried to run the tests and it started
complaining about something from the peak.util


On Nov 28, 2007 5:10 AM, Phillip J. Eby <pje at telecommunity.com> wrote:

> FYI, folks, if you're doing development against the SVN version of
> the Trellis, please be aware that a couple of major changes in
> semantics are coming soon, like in the next day or so.
> A quick summary of the major changes:
> * Rules can now make changes to other cells
> * Rules and modifiers can see the immediate effects of their changes
> (but still cannot see the calculated effects)
> * @trellis.action is no more: you will have to switch to @rule or
> @observer instead (where @observer is for communicating with
> non-trellis software and is not allowed to make changes)
> * non- at observer rules can be run more than once, and so must either
> be safe to re-run, or log their changes so the trellis can undo them
> * recalculation errors roll back all changes to the trellis
> * circular rules that would've led to an infinite loop can now be
> detected, with a complete report of the rules involved
> * @task rules now require an EventLoop to run, and they are no longer
> guaranteed to see all changes to the trellis.  In particular, they
> can no longer see receiver or discrete values, because those cells
> will reset before the eventloop can run.  On the other hand, because
> of this change, it is now potentially possible for code in one thread
> to trigger the resumption of a task running in another thread.  (The
> new algorithm has hooks for multi-thread locking, but it is not yet
> implemented.)
> This isn't a complete list of changes, but I believe it covers most
> of the big things.  I'm bumping the version from 0.5b2dev to 0.6a1dev
> to reflect the differences.  There will need to be some major
> documentation overhauls in the near future, as I have done almost no
> doc updates for the above, or to add information about the new STM
> (Software Transactional Memory) and recalculation controller objects
> and their APIs, or how to implement advanced data structures and
> specialized cell types under the new regime.
> Last, but far from least, my initial checkin isn't going to support
> undo for List, Dict, Set, etc., and so your code may act funny if a
> rule that modifies one of those structures needs to be undone due to
> an ordering issue.
> Hopefully, we'll have some stability on the trunk relatively soon,
> but the docs may take longer.  With luck -- and especially testing --
> perhaps we will have a solid 0.6 beta by year end.  If you'd like to
> help, please try your existing Trellis code bases against the new
> trunk once I announce the first checkin, and let me know of any
> issues, quirks, glitches, or oddities you may run into.  Thanks!
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There is NO FATE, we are the creators.
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