[Jython-users] Using jython with jythonc-compiled classes?

[Danny Y. <dy...@hk...>]

I've been experimenting with jythonc, and one of my experiments was to
play around with Java interfaces.  In the course of my experiments, I've
been running my head into a strange AttributeError.

Since I'm not too familiar with Jython, I'll report the steps I've done in
some detail; forgive me if much of this is extraneous!  The error message
is at the very bottom, and this message traces what I've done to get the
message.


I have the following Java interface:

###
[dyoo@tesuque bar]$ cat EvalInterface.java
public interface EvalInterface {
    public int eval(int x);
}
###


I've written a few Jython files that extend this interface:

###
[dyoo@tesuque bar]$ cat Doubler.py  
import EvalInterface

class Doubler(EvalInterface):
    def __init__(self):
        pass
    
    def eval(self, x):
        return x + x

[dyoo@tesuque bar]$ cat Squarer.py
import EvalInterface

class Squarer(EvalInterface):
    def __init__(self):
        pass
    
    def eval(self, x):
        return x * x
###


and I've compiled my Jython files into a single .jar file:

###
processing Doubler
processing Squarer

Required packages:

Creating adapters:

Creating .java files:
  Squarer module
    Squarer extends java.lang.Object implements EvalInterface
  Doubler module
    Doubler extends java.lang.Object implements EvalInterface

Compiling .java to .class...
Compiling with args: ['/usr/local/bin/jikes', '-classpath',
'/home/dyoo/local/jython-2.1a3/jython.jar:.:/opt/jdk1.3.0_02/jre/lib/rt.jar:/home/dyoo/local/jython-2.1a3/jython.jar:./test.jar:./jpywork::/home/dyoo/local/jython-2.1a3/Tools/jythonc:/home/dyoo/bar/.:/home/dyoo/local/jython-2.1a3/Lib',
'./jpywork/Squarer.java', './jpywork/Doubler.java']
0  
Building archive: test.jar
Tracking java dependencies:
###


Once this was done, I adjusted my CLASSPATH to include this jar file:

###
export
CLASSPATH=.:/opt/jdk1.3.0_02/jre/lib/rt.jar:\
/home/dyoo/local/jython-2.1a3/jython.jar:./test.jar
###

and wrote a small java test.java to see if everything worked.

###
[dyoo@tesuque bar]$ cat foo.java
public class foo {
    static public void main(String[] args) {
	EvalInterface f1 = new Square();
	System.out.println(f1.eval(42));
	EvalInterface f2 = new Double();
	System.out.println(f2.eval(42));
    }
}
###

And this worked!

###
[dyoo@tesuque bar]$ java Test
1764
84
###


However, I ran into problems when I tried playing with my classes in
Jython.  To force Jython to use my jythonc-compiled classes, I made a new
directory called "scratch".  Here's the log:

###
[dyoo@tesuque bar]$ mkdir scratch
[dyoo@tesuque bar]$ cp test.jar scratch/
[dyoo@tesuque bar]$ cd scratch
[dyoo@tesuque scratch]$ cp ../EvalInterface.class .
[dyoo@tesuque scratch]$ echo $CLASSPATH
.:/opt/jdk1.3.0_02/jre/lib/rt.jar:/home/dyoo/local/jython-2.1a3/jython.jar:./test.jar
[dyoo@tesuque scratch]$ jython
Jython 2.1a3 on java1.3.0_02 (JIT: null)
Type "copyright", "credits" or "license" for more information.
>>> import Doubler
>>> Doubler
<jclass Doubler at 5868800>
>>> d = Doubler()
>>> d.eval(42)
Traceback (innermost last):
  File "<console>", line 1, in ?
AttributeError: abstract method "eval" not implemented
###

I'm just scratching my head on this one.  Are Jythonc-compiled classes
reusable from Jython itself?  Any help on this would be greatly
appreciated.  Thank you!