For everything to work right, you always have to use the asterisks (as I said, 
they're part of the name), and you must include a (defglobal)  declaration 
before using the variable. Setting a global variable "by hand" without 
declaring it first produces undefined results (I.e., it'll work right some of 
the time.)

From: Hunter McMillen <<>>
Reply-To: <<>>
Date: Wed, 11 Jan 2012 16:37:11 -0500
To: <<>>
Subject: Re: JESS: [EXTERNAL] How to negate a variable when in lhs of a rule

I placed the asterisks around PLAYER_ID then still received an error when the 
rule fired: " No such variable *PLAYER_ID*" But then noticed that when I call 
setVariable, I name the variable PLAYER_ID not *PLAYER_ID* so I changed my 
statement to this:

engine.getGlobalContext().setVariable("*PLAYER_ID*", new Value(player.getID());

and everything works fine.

Does getGlobalContext().setVariable(...) define global variables implicitly? or 
do you have to include the asterisks like I did?

Hunter McMillen

On Wed, Jan 11, 2012 at 3:13 PM, Friedman-Hill, Ernest 
<<>> wrote:
The asterisks are part of the defglobal's name. You're not comparing to the 
defglobal: you're binding the value in the slot to a new variable. It's not 
legal to negate such a constraint in its first use, as the error message said. 
You need to use

 (unit (ID ?id) (typeID ?typeID) (player ~?*PLAYER_ID*))

From: Hunter McMillen <<>>
Reply-To: <<>>
Date: Wed, 11 Jan 2012 14:38:31 -0500
To: <<>>
Subject: JESS: [EXTERNAL] How to negate a variable when in lhs of a rule

Hi everyone,

I am trying to differentiate between Objects that belong to a certain user 
inside two of my rules.

I have a variable created from Java like this:

engine.getGlobalContext().setVariable("PLAYER_ID", new Value(player.getID());

And I want to use this variable in rules to determine which objects belong to 
each player.

This rule works fine when just using ?PLAYER_ID
(defrule myUnitSeen
   (unit (ID ?id) (typeID ?typeID) (player ?PLAYER_ID))

But when I try to negate the variable I get an error, "First use of variable 
negated: PLAYER_ID"
(defrule enemyUnitSeen
   (unit (ID ?id) (typeID ?typeID) (player ~?PLAYER_ID))

How can I specify anything other than ?PLAYER_ID on the lhs of a rule?

Hunter McMillen

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