Hi Folks,
One of my many failings is that I have a tendency to feel squeamish
about making changes to user-contributed code - it is, in my way of
thinking, an example of "looking a gift horse in the mouth." That
said, it should be obvious from the comments in Multifunctions.java
that much of the code in that file was a gift - a rather old one, at
that: it was first included in Jess 3.1.
Looking now at the functions for subsetp, union$, intersection$, and
complement$, I'm at a loss to explain the choice of algorithm. Jess
has changed a lot since then, and perhaps at the time these were
written, converting to strings and comparing the strings was the only
way to accomplish the task, but at the present time, the
Value.equals() method would serve much better. Note that at the time
of Jess 3.1, EXTERNAL_ADDRESS values may not yet have ever been used
by anyone, although the constant was defined.
I'll delay 5,0a3 by another day and rewrite these questionable
functions before the releae. Thanks for pointing these out.
I think Bob Orchard wrote:
>
> Take a look at the code in MultiFinctions.java and you'll see that to
> do the subsetp test the Values of the list are converted to strings
> with ToString and the type is appended to this string. These strings
> are used to compare and determine 'equality'. This probably works
> most of the time but external addresses (i.e. Objects like StringBuffer)
> convert to string as "External-Address:objectname". This means that
> for objects, all those of the same class are considered to be the same.
> I think this may be intentional (for performance perhaps),but I also
> think it should be done as you say via equals.
>
> Bob.
>
> Bob Johnson wrote:
>
> > Fellow Jessians,
> >
> > I need to populate multislots with Java objects and subsequently
> > perform multislot set comparisons. I was assuming that all
> > comparisons on external addresses would be accomplished via the Java
> > "public boolean equals(Object obj)" method. The following interaction
> > seems to prove otherwise:
> >
> > ----------------------------------------------------------------------
> > Jess, the Java Expert System Shell
> > Jess Version 4.3 12/3/98
> >
> > Output appears in this window.
> > Type your input in the one-line input box below.
> > Jess> (defglobal ?*buffa* = (new java.lang.StringBuffer "a"))
> > TRUE
> > Jess> (defglobal ?*buffb* = (new java.lang.StringBuffer "b"))
> > TRUE
> > Jess> (subsetp (create$ ?*buffa*) (create$ ?*buffb*))
> > TRUE
> > Jess> (subsetp (create$ "a") (create$ "b"))
> > FALSE
> > Jess> (call ?*buffa* toString)
> > "a"
> > Jess> (call ?*buffb* toString)
> > "b"
> > Jess> (call ?*buffa* equals ?*buffb*)
> > FALSE
> > Jess>
> > ----------------------------------------------------------------------
> >
> > Am I expecting something that I shouldn't or is this a bug?
> >
> > Regards,
> >
> > Bob
> >
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---------------------------------------------------------
Ernest Friedman-Hill
Distributed Systems Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
Org. 8920, MS 9214 [EMAIL PROTECTED]
PO Box 969 http://herzberg.ca.sandia.gov
Livermore, CA 94550
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