The Context object is analagous to the call stack in languages like C
and Java. Just as there's no language-level mechanism in those
languages to call a function with a user-specified stack, there's no
such mechanism in Jess, either.
You can, of course, pass a Context as a regular argument to a
function, which perhaps makes more sense here, anyway; or the function
might get the context using (fetch), or a defglobal, or some Java
global or static function -- or member function in the POC
class... there are many possibilities.
I think Mahesh Gandhe wrote:
>
> Hi ,
> I am calling user defined function in the rule (in the body of the rule).
> This function is called using the �test CE�.
> My query is how to explicitly pass the Context object to this user function call in
>the defrule?.I tried looking the manual and API but was not able to get the syntax.
> My requirement is that called user function does some modifications to the
>Context object passed to it.
>
> Here is an example
>
> This is the class for defining the user function:
>
> package edu.umbc.cs.D2J;
> import jess.*;
>
> public class POC implements Userfunction{
>
> public String getName() { return "try"; }
>
> public Value call(ValueVector vv, Context context) throws JessException
> {
> System.out.println("I am being called");
> /****** passed context changed *****/
> context.setVariable("third", new Value("check" ,RU.STRING));
> System.out.println("context aft= " + context);
> return new Value( new Boolean(true));
> }
> }
>
>
>
> This is the class which calls the function:
>
> package edu.umbc.cs.D2J;
>
> import jess.*;
> public class ExAddUF
> {
> public static void main(String[] argv) throws JessException
> {
> Rete r = new Rete();
> r.addUserfunction(new POC());
>
> r.executeCommand("(reset)");
> r.executeCommand("(bind ?x 123)");
>
> Context myContext = null;
>
>
> System.out.println(r.getGlobalContext());
>
> /****** here the unser function is called ****/
> r.executeCommand("(defrule abc (test(try 123)) => (assert (check 345)))");
> r.executeCommand("(run)");
> r.executeCommand("(facts)");
> }
> }
>
> in the defrule when I am calling try method I want to pass the myContext object as
>an parameter.
> What is the syntax for it?
>
> Thank you.
>
> Regards,
> Mahesh G.
>
>
>
>
>
>
> ---------------------------------
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> Yahoo! Greetings - send greetings for Easter, Passover
---------------------------------------------------------
Ernest Friedman-Hill
Distributed Systems Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
Org. 8920, MS 9012 [EMAIL PROTECTED]
PO Box 969 http://herzberg.ca.sandia.gov
Livermore, CA 94550
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