RE: JESS: [EXTERNAL] Adding facts that are instances of from-class deftemplates
The thing is that after this code: (deftemplate Person (declare (from-class Person))) (bind ?f (assert (Person (name Henrique) (age 38 There's no way to transfer those property values to a Person object; i.e., if you then said (modify ?f (OBJECT (new Person))) Then the Person's name and age would NOT be Henrique and 38; they'd be something else. The only way to get a shadow fact and a Java object synced up automatically is to let Jess copy the properties to the fact from the object. To unsubscribe, send the words 'unsubscribe jess-users y...@address.com' in the BODY of a message to majord...@sandia.gov, NOT to the list (use your own address!) List problems? Notify owner-jess-us...@sandia.gov.
Re: JESS: [EXTERNAL] Adding facts that are instances of from-class deftemplates
Got that, thanks a lot. Henrique On Thu, May 16, 2013 at 3:24 PM, Friedman-Hill, Ernest ejfr...@sandia.govwrote: The thing is that after this code: (deftemplate Person (declare (from-class Person))) (bind ?f (assert (Person (name Henrique) (age 38 There's no way to transfer those property values to a Person object; i.e., if you then said (modify ?f (OBJECT (new Person))) Then the Person's name and age would NOT be Henrique and 38; they'd be something else. The only way to get a shadow fact and a Java object synced up automatically is to let Jess copy the properties to the fact from the object. To unsubscribe, send the words 'unsubscribe jess-users y...@address.com' in the BODY of a message to majord...@sandia.gov, NOT to the list (use your own address!) List problems? Notify owner-jess-us...@sandia.gov. -- - - - - - - - - - - - - - Henrique Lopes Cardoso DEI/FEUP Rua Dr. Roberto Frias | 4200-465 Porto PORTUGAL VoIP: (+351) 220413355 Phone: (+351) 225081400 ext.1315...@fe.up.pt | www.fe.up.pt/~hlc - - - - - - - - - - - - -
Re: JESS: [EXTERNAL] Adding facts that are instances of from-class deftemplates
Thanks for the dog analogy... But going back to practical uses, one aspect that I like when creating a fact directly from a from-class template (i.e., a doghouse without a dog -- I can still make some reasoning over the doghouse) is that the Jess code to do it is much more readable and compact, since you provide values for named slots. Something like: (deftemplate Person (declare (from-class Person))) (assert (Person (name Henrique) (age 38))) When using definstance, I would have to go: (bind ?p (new Person Henrique 38)); assuming there is such a constructor (definstance Person ?p) or (bind ?p (new Person)) (?p setName Henrique) (?p setAge 38) (definstance Person ?p) Now, when you have a class with many data members this becomes quite complex. Any comments? Thanks! Henrique On Fri, May 10, 2013 at 3:21 PM, Friedman-Hill, Ernest ejfr...@sandia.govwrote: The **real** way to add shadow facts is using the “definstance” function. It has a number of options that aren’t available with “add”. The “add” function was added to Jess to support the simplified semantics of JSR-94 (the javax.rules API) but the intent is that most Jess users will use “definstance.” ** ** Asserting a fact directly from a from-class template is like buying a doghouse; you don’t expect to go out the next morning and find that somehow it has a dog in it, right? It’s certainly something you can do, but in normal life it’s not very useful; usually you get a doghouse when you buy a dog, and “add” and “definstance” will both get you a doghouse for your Java object “dog” automatically. ** ** *From:* owner-jess-us...@sandia.gov [mailto:owner-jess-us...@sandia.gov] *On Behalf Of *Henrique Lopes Cardoso *Sent:* Friday, May 10, 2013 4:54 AM *To:* jess-users *Subject:* JESS: [EXTERNAL] Adding facts that are instances of from-class deftemplates ** ** Hi, ** ** I am concerned with the at least two different ways in which you can add, to working memory, facts that are instances of from-class deftemplates.*** * Lets say I have: ** ** (deftemplate FC (declare (from-class FC))) ** ** I can add a shadow fact like this: ** ** (bind ?fc (new FC)) (add ?fc) ** ** This is the general approach described in Section 5.3.2 of the Jess manual. But I can also simply go like: ** ** (assert (FC)) ** ** I guess in this case I do not get a shadow fact, since the OBJECT slot is nil. ** ** So, my question is: if my facts are not supposed to be changed from Java code, is there any difference in using each of these approaches? Section 5.3 from the Jess manual does not even mention that instances of from-class deftemplates can be created using the second approach above.*** * ** ** Thanks! ** ** Henrique ** ** -- - - - - - - - - - - - - - Henrique Lopes Cardoso DEI/FEUP Rua Dr. Roberto Frias | 4200-465 Porto PORTUGAL VoIP: (+351) 220413355 Phone: (+351) 225081400 ext.1315...@fe.up.pt | www.fe.up.pt/~hlc - - - - - - - - - - - - -
RE: JESS: [EXTERNAL] Adding facts that are instances of from-class deftemplates
The *real* way to add shadow facts is using the definstance function. It has a number of options that aren't available with add. The add function was added to Jess to support the simplified semantics of JSR-94 (the javax.rules API) but the intent is that most Jess users will use definstance. Asserting a fact directly from a from-class template is like buying a doghouse; you don't expect to go out the next morning and find that somehow it has a dog in it, right? It's certainly something you can do, but in normal life it's not very useful; usually you get a doghouse when you buy a dog, and add and definstance will both get you a doghouse for your Java object dog automatically. From: owner-jess-us...@sandia.gov [mailto:owner-jess-us...@sandia.gov] On Behalf Of Henrique Lopes Cardoso Sent: Friday, May 10, 2013 4:54 AM To: jess-users Subject: JESS: [EXTERNAL] Adding facts that are instances of from-class deftemplates Hi, I am concerned with the at least two different ways in which you can add, to working memory, facts that are instances of from-class deftemplates. Lets say I have: (deftemplate FC (declare (from-class FC))) I can add a shadow fact like this: (bind ?fc (new FC)) (add ?fc) This is the general approach described in Section 5.3.2 of the Jess manual. But I can also simply go like: (assert (FC)) I guess in this case I do not get a shadow fact, since the OBJECT slot is nil. So, my question is: if my facts are not supposed to be changed from Java code, is there any difference in using each of these approaches? Section 5.3 from the Jess manual does not even mention that instances of from-class deftemplates can be created using the second approach above. Thanks! Henrique
