Re: Add/remove rules dynamically in CLIPS?

[CLIPS Support]

You can dynamically create new rules and these rules will match any preexisting facts. You can either load them from a file, enter them at the command prompt, or use the build command:

CLIPS> (defrule rule-1 (a) =>)

CLIPS> (assert (a) (b))

<Fact-2>

CLIPS> (agenda)

0      rule-1: f-1

For a total of 1 activation.

CLIPS> (defrule rule-2 (b) =>)

CLIPS> (build "(defrule rule-3 (a) (b) =>)")

TRUE

CLIPS> (agenda)

0      rule-3: f-1,f-2

0      rule-2: f-2

0      rule-1: f-1

For a total of 3 activations.

CLIPS> 

On Wednesday, June 5, 2013 6:56:24 AM UTC-5, anders....@gmail.com wrote:

Hi,

I'm implementing a Publish/Subscribe service where CLIPS rules defines the subscription. At anytime a device can create/remove a subscription so creating CLIPS rules must be performed dynamically. Is it possible to add and remove rules from CLIPS on the fly? For adding rules I guess I could write the new rule to a new clp file and Load it into CLIPS.

Thanks,

Anders Berg

[Nick Bassiliades]

You could also use the build function.
See CLIPS Basic Programming Guide page 165-166

Cheers,
Nick

Στις 5/6/2013 2:56 μμ, ο/η anders....@gmail.com έγραψε:
> Hi,
>
> I'm implementing a Publish/Subscribe service where CLIPS rules defines
> the subscription. At anytime a device can create/remove a subscription
> so creating CLIPS rules must be performed dynamically. Is it possible
> to add and remove rules from CLIPS on the fly? For adding rules I
> guess I could write the new rule to a new clp file and Load it into CLIPS.
>
> Thanks,
> Anders Berg

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[anders....@gmail.com]

Thank you guys, the Build(constructString) works great for adding rules!

Now I can't get the Undefrule function to work, 4.6.21 in Advance Programming Guide, for removing defined rules.

Here is some of the code i use:

int main()

{

...

    char *newRule;

    int ok;

    /* Create a new rule */

    newRule = "(defrule turn_off_all_lights \n\

        ?fact <- (turn_off_all_lights_action)\n\

        => \n\

        (retract ?fact) \n\

        (printout t \"Turning of all the lights\" crlf))";

    ok = Build(newRule);

    if (ok == 1) printf("Rule: %s\n\nwas created successfully!\n", newRule);

    else printf("Error creating rule: %s\n", newRule);

...

    /* Remove a defrule */

    char * removeRule = "turn_off_all_lights";

    void * rulePtr = FindDefrule(removeRule);

    ok = Undefrule(rulePtr);

    if (ok == 1) printf("Successfully deleted rule: turn_off_all_lights");

    else printf("Error: could not delete rule!!");

...

}

When i run my program it gets stuck at the "ok = Undefrule(rulePtr);" and the program never finishes.

The rulePtr is not NULL, so it finds the rule.

Any suggestions?

Thanks,

Anders

[CLIPS Support]

It worked when I tried in with version 6.3 of CLIPS. I would suggest removing the ... code in your example and see if it works properly in that case.

On Wednesday, June 5, 2013 6:56:24 AM UTC-5, anders....@gmail.com wrote:

[anders....@gmail.com]

I think I found the problem. I'm adding facts in between the defrule and undefrule, which activates the rule. So I'm trying to delete a rule that is in the agenda and haven't been fired yet.

I moved the Run(-1); function call before the undefrule function call and then it worked. Now I'll just have to figure out if I can remove an activated rule from the agenda and delete it before I call the Run() function =)