[kepler-dev] Can I use Ptolemy actors in Kepler?

Tony O'Hagan tohagan at itee.uq.edu.au
Thu Jun 21 19:43:39 PDT 2007

> From: Dan Higgins [mailto:higgins at nceas.ucsb.edu]
> Sent: Friday, 22 June 2007 8:34 AM
> To: Efrat Frank
> Cc: Norbert Podhorszki; Tony O'Hagan; Kepler-Dev
> Subject: Re: [kepler-dev] Can I use Ptolemy actors in Kepler?
> Hi All,
>     Just for your information, I am working on a system for showing an
> actor in the tree without loading it until it is dropped. I've still got
> some work to go, however.

Hi All,

This sounds very promising Dan.  Thanks very much for considering the option
of importing the Ptolemy actors.  I understand the issues in pulling it off
at the moment.

In my application requirements I've got nested loops of indefinite length.
I've found that I've had to bend my problem to fit the language (or my lack
of knowledge of it!) by imposing firing count limits (non indefinite) on the
outer loop at design time.  I'm then doing some weird linguistic yoga
writing composite actors that emit functions in order to apply them on
sequences of arrays. I would never expect non-IT scientists to pull off this
kind of functional programming.  These FP workflows are also rather
constrained to (mostly) using Kepler expression, constant and control flow
actors so it works for my current app but I can see that they will break if
in the future I needed to do things outside this space.

I finally realised that I was missing some of important Higher Order actors
from Ptolemy that would have simplified my solution. In essence I think that
Kepler either needs at least some of these actors in order to cover the
bases in expressability or perhaps some more examples to show how to pull
off complex iteration and control flow.  Of course there are also lots more
goodies in the Ptolemy tool chest that I wish were available in Kepler. The
sum would be definitely be far greater than the 2 parts as you'd continue to
leverage new Ptolemy actors over time.

I still haven't got my complete workflow going yet. It's been a more painful
process than I expected.  In part due to missing actors and actor features
and in part due to unclear or missing documentation.  As a full-time
research programmer I fully understand how & why this happens - I'm just on
the receiving end this time :).

Thanks again!

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