[kepler-users] Persistent objects, also: array element setting

Maurice Yarrow myarrow at nortel.com
Mon Feb 20 14:37:41 PST 2006

Hello Kepler/Ptolemy people

Please permit me at this time to expand to the Kepler/Ptolemy community
at large the context of some questions I sent on Saturday to Christopher

Does anyone have a simple example of a Java class that can be used in a
workflow model for persistent object data.  Is this an actor, in this
case ?

If it is possible to have such persistent data obj, how is it
referenced/designated from within actors ?  Could it be referenced from
within the Expression operator ? 

I guess along the same lines is the following question I have been
meaning to ask for a while.  How does one set a particular (indexed)
array element in an already declared array ?  I presume that this not
possible due to the rule of token immutability.  Is this so ?  

If it is not possible to set an array element, then I take it that the
only way is something like:  get the subarrays that are respectively
below and above the element to be set, and then use the Append array
actor to create a new array from the following three arrays:
{ E1,...,En-1 }   { En (new val) }  { En+1,...,Enmax }

This is a tiny bit ugly, no ?

Note that all of these questions directed to my effort to have
persistent data objects (or even structures, such as an array) that are
referenceable and mutable.  After all, as a workflow model becomes more
complex, the necessity for keeping state information around and for
accessing it grows.

Maurice Yarrow
Nortel Networks Research Labs
Santa Clara 

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