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  (IMA Internet Exchange v1.04) id 2b028aa0; Thu, 12 Dec 96 10:45:46 -0500
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Date: Thu, 12 Dec 1996 10:46:21 -0500
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Subject: Re: questions
To: Karl Lieberherr <lieber@ccs.neu.edu>
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Status: R

     See my answers below.


______________________________ Reply Separator _________________________________
Subject: questions
Author:  Karl Lieberherr <lieber@ccs.neu.edu> at SMTPGATE
Date:    12/12/96 8:35 AM


Art:
     
You write:
A ContainerClass must implement the following methods in order to be used in a 
Re petitionClass: 
     
void addElement(RepeatedPartType); 
     
synchronized Enumeration elements();
     
Why is addElement not synchronized?
If two elements are added simultaneously, couldn't one be lost?
     
     You are correct. I accidentally omitted "synchronized" from the 
     addElement declaration.
     
     These signatures come from the Vector class in java.util, with the 
     exception that it uses Object. This is okay, since Object is a 
     super-class of all objects, and therefore of RepeatedPartType.
     
     I will fix the documentation and put a new copy in 
     /proj/asl/lieber/f96/com3360/ahuston.
     
     Shouldn't all traversals in DemJava also be synchronized?
     
     
---------
In /proj/asl/lieber/f96/com3360/ahuston/example
please can you put in all the code generated by the modified 
Demeter/Java, specifically the *.java files.
This serves as a good example.

              Good idea. I'll do it.

---------
     
You write:
     
if (o instanceof repeatedpartype) { 
     
repeatedparttype repeatedpartpartname = (Value) o; 
     
repeatedpartname.traversal_name(visitorargname); 
     
} 
     
What is Value?

        I had copied an actual traversal over a RepetitionClass containing
        Value. I will change it to "repeatedparttype".
     
--------
     
Can you add a second example where the user defines his own 
container class with the required interface and uses it in 
a repetition class?
     
--------

     Hmm. I have an idea about extending a HashTable to be a ContainerClass 
     to store a list of employees. It should be straight-forward, and a 
     good example as well. I can't do it today because I have work, the 
     final exam, and my son's Christmas concert tonight. But I think I can 
     do it by Monday.
     
Please can you give me step-by-step instructions how I need to 
change my set-up to run your new version of Demeter/Java.
     
     I did not copy any of the object code or executables to 
     /proj/asl/lieber because I did not want to use too much disk space. 
     Was this a mistake? If so, I can copy it.
     
     For now, you should add /proj/demsys/com3360/ahuston/project/bin to 
     your PATH so it appears before /proj/demsys/demjava/bin. I believe you 
     have execute privileges.
     
     I deleted the executable to save space, so I am rebuilding it now. 
     I'll send email when everything is ready.
     
-- Karl

     Thanks for the comments. See you tonight.

                                        Art