Re: [Jython-users] Subclassing java classes in jython: problem with exceptions

[Andres H. <an...@gf...>]

On Fri, 4 Nov 2005, Diez B. Roggisch wrote:

> > I thought I have to add @sig to any method I use from java. If I make
> > this modification in your code, it will not work:
> > 
> > class Foo(test.Test):
> > def doNothing(self):
> >    """@sig public void doNothing()"""
> > raise test.Test.Whatever()
> > 
> > Thanks for the working example!
> > 
> I can't reproduce that. AFAIK @sig is only needed in case of using jythonc,
> _and_ wanting to introduce new methods that the compiled class should have,
> but which aren't part of the subclassed one - either interface or base class.
> 
> And I'm pretty sure the throws clause the is part of the signature, too. Which
> you are missing, and maybe that causes the problems you see.

I am using jythonc. In my case the main program is in java and it 
instantiates classes that are implemented in Python.

It is not possible to add "throws" clause to @sig. This causes a jythonc 
compilation error:

"""@sig public void doNothing() throws Whatever"""

I found references to that problem also on the mailing list. Without 
"throws" clause, PyException is thrown.

Your example works fine if I leave out @sig altogether. I am going to 
check if I can leave out @sig if the method returns non-void and has 
parameters, like:

class Foo(test.Test):
    def doNothing(self, x):
        if x == 0:
            raise test.Test.Whatever()
   
        return x

Andres.