Hi,
Two-part answer.
First, you can of course create the argument to "build" by calling
other Jess functions; that's what you need to do here. The "str-cat"
function pastes together the values of its arguments into one string;
the value of a variable is of course the contents of that variable.
So something like this:
(build (str-cat "(defrule checkLeave_" ?userName "
(user (name " ?userName ") (isInRoom ~Office1))
=>
(printout t User " ?userName " \" has left
Office1\" crlf))"))
If you look carefully, you'll see that all three occurrences of ?
userName are outside the string quotes.
Now, second: rather than creating a new rule in this case, consider
instead using a single rule and creating relevant data instead. So,
for example, just one rule like:
(defrule checkLeave
?m <- (watch-to-leave (name ?userName) (room ?room))
(user (name ?userName) (isInRoom ~?room))
=>
(retract ?m)
(printout t "User " ?userName " has left " ?room crlf))
Now, when you want to watch that Fred stays in Office1, you just
assert a fact like
(watch-to-leave (name Fred) (room Office1))
This is a much more efficient way to do what you want.
On Jan 4, 2008, at 12:52 PM, [EMAIL PROTECTED] wrote:
Hello, I'm a relatively new Jess user and I'm having difficulties
with a rule. I need to create a rule for a context-aware
application that monitors if a user leaves a room. For that a have
the following deftemplate:
(deftemplate user
(slot name)
(slot isInRoom))
The rule should notify me whenever someone leaves an specific room.
The solution I imagined has the following LHS
(defrule ruleCheckLeaveRoom
(user (name ?userName) (isInRoom Office1))
My problem is that the RHS should create (using build) another rule
for each person entering Office1. I tried the following but
couldn't have a variable as part of the second rule's name:
(build "(defrule (checkLeave_?userName
(user (name ?userName) (isInRoom ~~Office1))
=>
(printout t User ?userName has left Office1 crlf)
)")
I also need to substitute the variable ?userName for its value so I
can have the generation of the second rule like:
(defrule (checkLeave_John
(user (name John) (isInRoom ~Office1))
=>
(printout t User John has left Office1 crlf)
)
Is it possible? Do you have a suggestion for another solution?
Thanks,
Luiz Olavo Bonino
University of Twente
---------------------------------------------------------
Ernest Friedman-Hill
Informatics & Decision Sciences Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
PO Box 969, MS 9012 [EMAIL PROTECTED]
Livermore, CA 94550 http://www.jessrules.com
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