[Jython-dev] More on sys.excepthook patch alternatives

[Paul D. F. <pdf...@ku...>]

As I become more familiar with Jython and thinking like a Jython/Java 
developer as opposed to a Python/C developer, it occurs to me (with a 
shock of blinding obviousness (*)) that there is another way to approach 
the situation of getting a Jython sys.excepthook function to be called for 
Swing exceptions. And that is to use only Jython code to set up the 
machinery inside the JVM to do this.

So, for example, I know I can do this in Jython:
     from java.lang import System
     System.setProperty("sun.awt.exception.handler",
         "org.python.util.AwtExceptionHandler")

So, this can address at least the issue of whether there needs to be a 
global flag; there does not need to be a flag except as a convenience 
since someone could just instead put these two lines of code in their 
Jython program -- if there was a class that could be set as the second 
argument. I just tried this on my system using the stock Jython2.1 jar and 
it actually worked -- because I also still had the patched Jython from CVS 
in the path after it -- so I think Java looked around and still found my 
added class, even though it was running the unpatched Jython version. 
After I removed that project from the class path, the regular exception 
handler was called and my custom one was not, giving me more confidence 
that is what happened.

So, while I haven't tried this yet, I think I could possibly compile that 
one class, AwtExceptionHandler and have it in a jar file in my path, and 
otherwise use an unpatched Jython version. But I don't want to bother 
trying that if I could do something easier.

So, ideally I would like the AwtExceptionHandler class to be written in 
Jython too. So, then this becomes more a Jython user question, but what 
package in the second argument could I specify to System.setProperty() for 
a Jython class in a Jython MyCode.py file to be able to do this? If there 
is an answer, then anyone could catch Swing exceptions with just a few 
lines of Jython added to their Jython projects.

--Paul Fernhout
(*) It might have helped that I just spent hours figuring out how to get a 
JTextPane to do a client side (no server) callback to Jython on an HTML 
Form submit. Definitely gave me a better appreciation for how Jython and 
Java can work together.