There are (obviously) two options: (a) put the object somewhere accessible, and 
run Jess code that retrieves it, or (b) use Jess's Java API to set a Jess 
variable to contain the object. Either would work. The store/fetch mechanism is 
sort of an built-in easy way to do (a). Alternatively, say there's a global 
variable ?*x* defined in your Jess program. Then you can say

engine.getGlobalContext().setVariable("*x*", new Value(unit));

and your Jess code can later get the value of "*x*".

If you don't like using variables this way, there's always directly invoking 
Jess functions from Java. Here we invoke 'add' to add the object to working 
memory directly:

new Funcall("add", engine).arg(new 

From: [] On 
Behalf Of Hunter McMillen
Sent: Friday, November 04, 2011 1:08 PM
To: jess-users
Subject: JESS: Is it possible to bind a Java object directly to a Jess variable 
without creating a new object?

Hi everyone,

I am trying to assert to Jess that an object exists when I encounter a new 
object in my Java program. Right now I am using a template to mirror that 
object (i.e I have slot values for all of the Java objects fields)  but this 
seems redundant to me. Is there any way to just bind a Java object to a Jess 
variable without creating a new Java object?

A lot of the examples I see online and from JIA are of the form:
(bind ?map (new HashMap))


(call Classname method params...)

but these either create  a new object or call static methods. I already have 
the Java object and just want to store it.

But I was hoping that there was someway I could do something like this:
public Rete engine = new Rete();

public void unitDiscovered()
    Unit unit = <some unit encountered>; //Java object
    engine.executeCommand("(bind ?unit unit)");
    engine.executeCommand("(assert ?unit)");

Or would I have to use the store() and fetch() methods for this?

public void unitDiscovered()
    Unit unit = <some unit encountered>; //Java object"UNIT", unit);
    engine.executeCommand("(bind ?unit (fetch "UNIT")");
    engine.executeCommand("(assert ?unit)");

Basically I want to know the best practice for binding Java objects to Jess 
variables so I can assert them to the engine.

Hunter McMillen

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