[kepler-users] Optional port values

[Ian Szarka]

Hello,

I am looking for help trying to create a reusable composite actor with an optional port. 
The actor has an input port, a result port, and an optional string port to specify a file name to save the result.
I have tried using a PortParameter with no success. 

What I have been doing:

Create a blank workflow, 
Drag a SDF director, [set iterations to 1!]
Drag a composite actor

In composite actor: 
Add normal port for input, 
Add PortParameter, for optional string, edit with a unique value
Add normal port for output,
Drag String Accumulator actor,
Connect input to "Input" port and "Optional" Port to String Accumulator
Link String Accumulator to output port
Close composite actor

Drag 2 X String Constant and edit with unique values
Link a String Constant to input port
Link a String Constant to optional port
Drag Display actor,
Link output port to Display actor

Run, OK,

Removing the String Constant linked to the optional port 
Run, Error
"ptolemy.actor.sched.NotSchedulableException: Actors remain that cannot be scheduled!"

Opening the composite actor and adding a SDF director, [- see discussion in PortParameter documentation]
Run, The default optional value is nowhere to be seen.

Re-link a string constant to the optional port 
Run, The constant value is nowhere to be seen.

Cheers,
Ian.