Ernest,
I'll probably be the first of many to
point out the obvious fact that no
matter what you decide, it won't please
everybody. ;)
Having said that, from an interface encapsulation and robustness
point of view, I would want to see the Wrapper object,
not the primitive type.
In my experience with development, interfaces/boundaries
that return primitive types have a nasty habit of causing
rippling effects if either the interface changes, or the underlying
machine representation/constraints of the primitive change.
(Like depending on the Date or String type characteristics gotten from a
database,
but now you change underlying databases, for example.)
So, I vote for the Wrapper object.
---------------
George Rudolph
Mad Scientist
Motorola ISD
---------------
<*>-----Original Message-----
<*>From: [EMAIL PROTECTED]
<*>[mailto:[EMAIL PROTECTED]]
<*>Sent: Thursday, October 19, 2000 12:04 PM
<*>To: Lucero, Michael
<*>Cc: '[EMAIL PROTECTED]'
<*>Subject: Re: JESS: Java to Jess type conversion
<*>
<*>
<*>Hi Michael,
<*>
<*>I can confirm this behaviour in Jess 6, too. It's actually not just
<*>field access, but method return values too -- i.e., the return value
<*>of a method returning Integer would be similarly converted.
<*>
<*>It is arguably incorrect for this conversion to be done at all; I'm
<*>not sure what I was thinking when I defined it this way. I
<*>believe the
<*>current behaviour was influenced by user comments on the behviour of
<*>Java Strings. Several people expressed the opinion that a method
<*>returning String should return a Jess string when called from Jess,
<*>not an external address with a Java String in it.
<*>
<*>Let me throw this one out for comment. If you call a method
<*>or fetch a
<*>field of type Integer (or Float, or Double, or Boolean) should it
<*>return the primitive type in Jess, as it does now, or should
<*>it return
<*>the wrapper object? What do people think?
<*>
<*>
<*>I think Lucero, Michael wrote:
<*>[Charset iso-8859-1 unsupported, filtering to ASCII...]
<*>> Using Jess 5.1:
<*>>
<*>> if I have a class like this:
<*>>
<*>> public class A
<*>> {
<*>> public final static Object VAR = new Integer(1);
<*>>
<*>> public void setValueById(Object id)
<*>> {
<*>> m_val = id;
<*>> }
<*>>
<*>> private Object m_val,
<*>> }
<*>>
<*>> and rules (forgive syntax errors):
<*>>
<*>> (defclass classA A)
<*>>
<*>> (defRule varTest
<*>> (classA (OBJECT ?o))
<*>> =>
<*>> (call ?o setValueById (get-member A VAR))
<*>> )
<*>>
<*>> I get an exception when the rule fires:
<*>> Message: No overloading of method 'setValueById' in
<*>class A I can call
<*>> with these arguments: (call ?o setValueById (get-member A VAR)).
<*>>
<*>> I think the problem here is that 'get-member' does not
<*>return an external
<*>> address, but has translated it to a Jess Integer type.
<*>>
<*>> Is this expected, and, if so, is there a way to prevent
<*>that automatic
<*>> translation.
<*>>
<*>> Thanks in advance
<*>>
<*>> Michael Lucero
<*>>
<*>---------------------------------------------------------------------
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<*>---------------------------------------------------------------------
<*>>
<*>
<*>
<*>
<*>---------------------------------------------------------
<*>Ernest Friedman-Hill
<*>Distributed Systems Research Phone: (925) 294-2154
<*>Sandia National Labs FAX: (925) 294-2234
<*>Org. 8920, MS 9012 [EMAIL PROTECTED]
<*>PO Box 969 http://herzberg.ca.sandia.gov
<*>Livermore, CA 94550
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