[SOLVED] Jess-Rule : Str-Cat in Field comparison doen't compile

Jess-Rule : Str-Cat in Field comparison doen't compile

I wan't to match a value (String) of an jess-object and the comparative value is a combination of a string and another field.

Here a simple ("runnable") example:

(defclass Person (is-a :THING) (slot name (type string)) (slot email (type string))) 
(mapclass Person)

(make-instance Andy of Person (name "Andy") (email "Andy@mail"))

(defrule search 
(object (OBJECT ?tmpPerson)
    (is-a Person)
    (email (str-cat (slot-get ?tmpPerson name) "@mail"))
) 
=> 
(print t "found")
)

But the code doesn't compile in JessTab. It seems, that after the field-name "name" the "(" isn't allowed.

Error:

Jess reported an error in routine Jesp.parsePattern.
  Message: Bad slot value at token '('.
  Program text: ( defrule search ( object ( OBJECT ?tmpPerson ) ( is-a   Person ) ( name (  at line 5.

How can I fix this?

Thanks in advance

Solution

To match a pattern to the value returned by a function, you have to precede the function call with an equals sign -- i.e., "(name =(str-cat ..."