Defining "anonymous" rules in CLIPS - clips

Question

I know that rules in CLIPS are usually given names using defrule. This rule is called rule1:
(deftemplate animal (slot species))
(deffacts animal
(animal (species dog)))
(defrule rule1
(animal (species ?name))
=>
(printout t ?name crlf))
(reset)
(run)
(exit)
;
But I still don't know whether it is necessary for the rules to be named. Is it possible to define a rule without giving it a name, like this?
(deftemplate animal (slot species))
(deffacts animal
(animal (species dog)))
(defrule
(animal (species ?name))
=>
(printout t ?name crlf))
(reset)
(run)
(exit)
;

Answer 1

From section 5 of the Basic Programming Guide:
(defrule <rule-name> [<comment>]
[<declaration>]
<conditional-element>*
=>
<action>*)
The rule name is required.
To dynamically generate a rule name, use the gensym* function which creates a unique symbol:
CLIPS>
(deffunction create-anonymous (?conditions ?actions)
(bind ?str (str-cat "(defrule " (gensym*) " "
?conditions " => " ?actions ")"))
(build ?str))
CLIPS> (deftemplate animal (slot species))
CLIPS>
(create-anonymous "(animal (species ?name))"
"(printout t ?name crlf)")
TRUE
CLIPS> (rules)
gen1
For a total of 1 defrule.
CLIPS> (ppdefrule gen1)
(defrule MAIN::gen1
(animal (species ?name))
=>
(printout t ?name crlf))
CLIPS>