Re: [eclipse-clp-users] Java error messages

From: Kish Shen <kisshen_at_...5...>
Date: Wed, 04 Mar 2009 01:29:43 +0000
Hi Gregory,

 From your message, I am not sure if you want to debug your ECLiPSe code 
in Java, or if it is to write error handling code for ECLiPSe in Java.

In both cases, I think it is best to try to do as much in ECLiPSe rather 
than Java. ECLiPSe is a full programming language, so in general it is 
much better to do development and handle programming tasks in it. On the 
other hand, the Java interface (and indeed the other interfaces of 
ECLiPSe to external languages) are not really designed for doing ECLiPSe 
programming development through the interface.

For debugging, if possible, you should try and develop your ECLiPSe code 
using ECliPSe's development environment (Saros, as suggested by Paul, or 
TkECLiPSe) before connecting it to Java. If this is not possible, and 
you must debug your ECLiPSe code while running it through Java, you can 
use lib(remote_tools) to connect the ECLiPSe development tools (used in 
TkECLiPSe and also Saros) to any process running ECLiPSe code, even if 
you are using RemoteECLiPSe and the ECLiPSe process is running on a 
different machine from your Java code (and your remote tool -- you do 
need to have ECLiPSe on your local machine so that you can run the 
remote tools there).

For writing error handling code for ECLiPSe, this is best done in 
ECLiPSe itself. By the time the execution of an ECLiPSe goal returns to 
Java with an exception, it is rather late to handle the error (in 
addition to the lack of facilities to do so).  Error handling in ECLiPSe 
is discussed in the Events and Interrupts chapter of the User manual 
(section 13.2 in the current version):

http://www.eclipse-clp.org/doc/userman/umsroot072.html

One way of handling errors would be to write your own error handlers for 
the errors you want to handle, and in your error handler, you can 
communicate with Java, giving your Java code the information you need on 
the Java side about the error.

The default ECLiPSe error handlers should print their error messages in 
the ECLiPSe error stream. Depending on how you set up your ECLiPSe peer, 
  the error stream can either be connected to your JVM's stderr, or you 
can connect it to your own FromECLiPSeQueue, this will allow you to see 
the error message on the Java side, if you don't write your own error 
handling code.

Hope the above helps,

Kish

Gregory Harman wrote:
> Hi all,
> 
> I'm fairly new to ECLiPSe, and am planning on using it as a supplement  
> to a Java codebase. I've gotten basic communication between Java and  
> ECLiPSe working via the parctechnologies library, but I'm struggling a  
> bit with the error handling: when I execute a goal that causes an  
> ECLiPSe error, I get a com.parctechnologies.eclipse.Throw returned to  
> my Java class (as I should, according to the embedding documentation),  
> but there is no error message associated with that Throw to help me  
> debug. How can I coerce the system into giving something more to work  
> with than just "there was an error"?
> 
> Thanks for any pointers.
> 
> -Greg
> 
> 
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Received on Wed Mar 04 2009 - 01:29:51 CET

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