JessUserFunctions

• When you write a new function for JESS, you do it by writing a class that implements the jess.Userfunction interface.
• Then a single instance of this class is created and installed into JESS.

	rete.addUserfunction(new MyFunction?());
	rete.addUserpackage(new MyPackage?());
	(load-function "myfunction")
	(load-package "mypackage")

• Writing Extensions - require two methods: name() and call().

	import jess.*;
	public class MyUpcase? implements Userfunction
	{
	  // The name method returns the integer representation of the name.
	  // This function will be called by Jess.
	  public int name() { return RU.putAtom("my-upcase"); }

	  public Value call(ValueVector? vv, Context context)	throws ReteException?
		{
		return new	Value(vv.get(1).stringValue().toUpperCase(), RU.STRING);
		}
	}

• Executing this code.

	// Add the 'my-upcase' command to Jess
	rete.addUserfunction(new MyUpcase?());
	// Exceute some Jess code that calls this function
	rete.executeCommand("(printout t (my-upcase foo) crlf)");

		[JessInJava | JessAndAgents | NrcPammAgents]