jython-users — Discussion of and questions about using Jython

Re: [Jython-users] NullPointerException error when calling a python method

[yoshizak <yos...@da...>]

Hi there,
I was looking at the error message and the problem with PyProxy lead me 
to think I should put the jython.jar into the class path (I believe I 
saw another e-mail in the user archives that said something about this)
don't exactly know why I needed to do this, since I had presumed that 
this was done by default but when I ran my code sample with
java -classpath <some directory tree>/jython-2.0/jython.jar:. tryJythonMain
it finally seemed to run. (Yeah! Finally! :)
Question is, why did I need to do this? I mean, I'm sure not 'everyone' 
actually specifies the jar file when running their programs. Do I really 
need to specify the jar file in the classpath (or CLASSPATH)?
In any case, I seem to be able to continue on so thanks for all the 
help! Appreciate it greatly!
Hubert :)

[Jython-users] break infinite loop

[Jeff E. <je...@ad...>]

I drive my app from the jython interpreter command line.  Sometimes
I'll do something stupid and create an infinite loop (in jython code).
Currently, I have to kill the entire process.  I'd rather be able to
somehow tell the interpreter to break out of the current command that
it is processing and return to the command line so I can preserve as
much application state as possible.  Any suggestions?

Jeff Emanuel

Re: [Jython-users] ImportError: no module named java

[Ihab A.B. A. <ih...@ah...>]

Hi all,

Thanks Robert Bill & Jim Adrig for the tips....

> Yes, os requires the javaos module, and you get the ImportError when that
> module cannot be Located. Fix= make sure module is found.

I've been trying, in every manner possible! Here's my code --

  rootPath = servletContext.getRealPath("/");
  if (!rootPath.endsWith(File.separator)) rootPath += File.separator;

  Properties p = getInitParametersAsProperties();
  p.put(
    "python.cachedir",
    servletContext.getAttribute("javax.servlet.context.tempdir").toString());
  PythonInterpreter.initialize(System.getProperties(), p, new String[0]);

  PySystemState pySys = Py.getSystemState();
  pySys.add_classdir(rootPath + "WEB-INF" + File.separator + "classes");
  pySys.add_extdir(rootPath + "WEB-INF" + File.separator + "lib");
  pySys.path.append(new PyString(servletContext.getAttribute("python.home") +
    File.separator + "Lib"));
  pySys.path.append(new PyString(rootPath + "WEB-INF" + File.separator +
   "py"));

  pythonInterpreter = new PythonInterpreter(null, pySys);

I think, based on looking at PyServlet.java, that this should get all my 
bases covered. However, I still get --

  import os
  dir(os)

  Traceback (innermost last): File "", line 10, in ? ImportError: no
    module named javaos 

  import os
  print os.listdir('/home/ihab')    

  Traceback (innermost last): File "", line 2, in ? AttributeError: class
    'org.python.modules.os' has no attribute 'listdir' 

This is all very confusing. Any help appreciated from anyone. Peace,

Ihab

-- 
Ihab A.B. Awad <ih...@ah...>
Center for Computational Genomics and Bioinformatics,
University of Minnesota. http://www.cbc.umn.edu/~ihab/

Re: Re: [Jython-users] NullPointerException error when calling a python method

[yoshizak <yos...@da...>]

Hi Robert,
Haven't been able to reply for awhile because of other business stuff, in
anycase the situation changed a little though the result is largely the 
same
(not working yet)

 >I'm not sure this helps, but the code you list below works fine for me
 >(linux+sunJDK1.3).  One thing that might be worth checking is whether
 >the tryJythonSample class actually exists in a file called
 >"tryJythonSample.py".  The matching classname/filename is required here,
 >and a difference in those names makes a NPE like you are seeing.
 >
 >If that's no help, check back again :)
 >
 >-robert

Well, getting back to you here's the situation.
I'm now using Linux Mandrake 8.1
with sun's JDK1.3.1
and running jython 2.0

anyhow, I did the following,

jythonc tryJythonSample.py               (same result with --all option)
(all code at end of email)

copied the compiled code from the jpywork directory into the current one
(cp jpywork/* .)

javac -classpath /<directory tree>/jython-2.0:. tryJythonMain.java

java tryJythonMain

Exception in thread "main" java.lang.NoClassDefFoundError:
org/python/core/PyProxy
        at java.lang.ClassLoader.defineClass0(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:486)
        at
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:111)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:248)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:297)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:286)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:253)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:313)
        at tryJythonMain.main(tryJythonMain.java:10)


Any ideas what this is all about? There is obviously something that I'm 
doing
very wrong since something this simple should work no?

Thanks in advance,
Hubert
btw, tried with
jythonc --package tryJythonPackage tryJythonSample.py
with the corresponding javac code and slight changes to the source code 
(i.e.
import etc.) And I still get the same error message when I run it.
As for the reason to go to Linux from win2k, my machine (which was used by
someone else before) was not a clean machine. It had (cound them) three 
jdk's
but a bunch of other junk that should not be there so in the interest of
killing as many portential problems as possible I switched to Linux (though
admitedly, Mandrake may not be the greatest for development).

===================================================================
code

tryJythonSample.py

import java
class tryJythonSample(java.lang.Object):
        def __init__(self):
            "@sig public tryJythonSample()"
            print "Constructor for tryJythonSample"
        def makeObject(self):
            "@sig public void makeObject()"
            print "I have just called a python method!!"



tryJythonMain.java

import org.python.core.*;
import tryJythonSample;

public class tryJythonMain
{

        public static void main(String[] args)
        {

                tryJythonSample jySample = new tryJythonSample();
                jySample.makeObject();

        }
}

Re: Re: [Jython-users] NullPointerException error when calling a python method

[Hubert Y. <hyo...@ho...>]

Hi Robert,
Haven't been able to reply for awhile because of other business stuff, in
anycase the situation changed a little though the result is largely the 
same
(not working yet)

 >I'm not sure this helps, but the code you list below works fine for me
 >(linux+sunJDK1.3).  One thing that might be worth checking is whether
 >the tryJythonSample class actually exists in a file called
 >"tryJythonSample.py".  The matching classname/filename is required here,
 >and a difference in those names makes a NPE like you are seeing.
 >
 >If that's no help, check back again :)
 >
 >-robert

Well, getting back to you here's the situation.
I'm now using Linux Mandrake 8.1
with sun's JDK1.3.1
and running jython 2.0

anyhow, I did the following,

jythonc tryJythonSample.py               (same result with --all option)
(all code at end of email)

copied the compiled code from the jpywork directory into the current one
(cp jpywork/* .)

javac -classpath /<directory tree>/jython-2.0:. tryJythonMain.java

java tryJythonMain

Exception in thread "main" java.lang.NoClassDefFoundError:
org/python/core/PyProxy
        at java.lang.ClassLoader.defineClass0(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:486)
        at
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:111)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:248)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:297)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:286)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:253)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:313)
        at tryJythonMain.main(tryJythonMain.java:10)


Any ideas what this is all about? There is obviously something that I'm 
doing
very wrong since something this simple should work no?

Thanks in advance,
Hubert
btw, tried with
jythonc --package tryJythonPackage tryJythonSample.py
with the corresponding javac code and slight changes to the source code 
(i.e.
import etc.) And I still get the same error message when I run it.
As for the reason to go to Linux from win2k, my machine (which was used by
someone else before) was not a clean machine. It had (cound them) three 
jdk's
but a bunch of other junk that should not be there so in the interest of
killing as many portential problems as possible I switched to Linux (though
admitedly, Mandrake may not be the greatest for development).

===================================================================
code

tryJythonSample.py

import java
class tryJythonSample(java.lang.Object):
        def __init__(self):
            "@sig public tryJythonSample()"
            print "Constructor for tryJythonSample"
        def makeObject(self):
            "@sig public void makeObject()"
            print "I have just called a python method!!"



tryJythonMain.java

import org.python.core.*;
import tryJythonSample;

public class tryJythonMain
{

        public static void main(String[] args)
        {

                tryJythonSample jySample = new tryJythonSample();
                jySample.makeObject();

        }
}

[Jython-users] JythonInterpreter 0.6 beta

[Carlos Q. <car...@rt...>]

Hi all (I sent this message yesterday but it didn't appear, if it is
posted
twice I apologize)

I just released a new beta version of JythonInterpreter 0.6 plugin for
jEdit,
This version has a completely new GUI which follows more closely a
"traditional" jython/python interpreter. The new plugin is also almost
completely made in jython.

some new features:

- Completely rewritten GUI featuring a text area where you can write
jython commands, it also allows for copy/paste operations
- New check version commands which detects if an older version of jython
is
in the classpath
- New copyright/credits/license command
- History keys as CTRL+UP and CTRL+DOWN
- Error button. When an error is detected a button is appended to the
traceback which jumps to the error source
- Run current buffer button
- Run current buffer and print results to a new buffer
- Import current buffer
- Path Handler which allows you to easily modify the Jython Path. The
path is
modified at runtime allowing to load jar files without restarting. The
path
can be stored and loaded again the next time jython starts
- Path Browser, allows you to browse the system path, currently is
limited
to display only non-compressed files

Some limitations:
- Path Browser and Error button are not working with compressed files
- Some exceptions are not displayed in the Jython window but in the
activity
log
- Documentation has not been updated
- Probably many more (it is beta :-))

The plugin can be found here:

http://koti.welho.com/cquiroz/jedit/jython/JythonInterpreter.jar

The simplest way to install is to first install JythonInterpreter 0.5
using
jEdit's PluginManager and replace the JythonInterpreter.jar file with
the one
from the link.

NOTE: This plugin will only work with jython 2.1a3

Regards

Carlos Quiroz

Re: [Jython-users] ImportError: no module named java

[Robert W. B. <rb...@di...>]

Hello Ihab,

On Sun, 21 Oct 2001, Ihab A.B. Awad wrote:
>
> Yet more re this ... sorry for the proliferation of msgs.
>
> (a) I realized that "no module named java" was because my programs were
>     not specifying a "python.cachedir" property correctly. Fixing this has
>     fixed the original problem.

Good.

> (b) Now, running inside my JSP application (which is where I _really_ want
>     to use Jython), when I do --
>
>       import os
>       dir(os)
>
>     I get the error --
>
>       ImportError: no module named javaos
>
>     Eek. So, now, does _that_ look familiar to anyone?

Yes, os requires the javaos module, and you get the ImportError when that
module cannot be Located. Fix= make sure module is found.
Check your python.home/sys.path vars.  Use PythonInterpreter.initialize
before instantiating the interpreter to set properties like python.home so
modules can be found.  The org.python.util.PyServlet code is the best
example of setting properties and the initialize method.


-robert

RE: [Jython-users] ImportError: no module named java

[Jim A. <Ji...@do...>]

javaos.py is needed for the os module and should be in the Lib directory
under your jython.jar.

I don't know why it's not being found in your situation, try adding to your
classpath?

> -----Original Message-----
> From: Ihab A.B. Awad [mailto:ih...@ah...]
> Sent: Sunday, October 21, 2001 6:32 PM
> To: jyt...@li...
> Subject: Re: [Jython-users] ImportError: no module named java
> 
> 
> 
> Yet more re this ... sorry for the proliferation of msgs.
> 
> (a) I realized that "no module named java" was because my 
> programs were
>     not specifying a "python.cachedir" property correctly. 
> Fixing this has
>     fixed the original problem.
> 
> (b) Now, running inside my JSP application (which is where I 
> _really_ want
>     to use Jython), when I do --
> 
>       import os
>       dir(os)
> 
>     I get the error --
> 
>       ImportError: no module named javaos 
> 
>     Eek. So, now, does _that_ look familiar to anyone?
> 
> Thanks as always to all and peace,
> 
> Ihab
> 
> -- 
> Ihab A.B. Awad <ih...@ah...>
> Center for Computational Genomics and Bioinformatics,
> University of Minnesota. http://www.cbc.umn.edu/~ihab/
> 
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> https://lists.sourceforge.net/lists/listinfo/jython-users
> 

Re: [Jython-users] ImportError: no module named java

[Ihab A.B. A. <ih...@ah...>]

Yet more re this ... sorry for the proliferation of msgs.

(a) I realized that "no module named java" was because my programs were
    not specifying a "python.cachedir" property correctly. Fixing this has
    fixed the original problem.

(b) Now, running inside my JSP application (which is where I _really_ want
    to use Jython), when I do --

      import os
      dir(os)

    I get the error --

      ImportError: no module named javaos 

    Eek. So, now, does _that_ look familiar to anyone?

Thanks as always to all and peace,

Ihab

-- 
Ihab A.B. Awad <ih...@ah...>
Center for Computational Genomics and Bioinformatics,
University of Minnesota. http://www.cbc.umn.edu/~ihab/

Re: [Jython-users] ImportError: no module named java

[Ihab A.B. A. <ih...@ah...>]

Hi again,

According to "Ihab A.B. Awad" on Sunday 21 October 2001 20:32:
>
>   interp.exec("import java.lang");
>   interp.exec("print java.lang");
>
> I get the error --
>
>   Exception in thread "main" Traceback (innermost last):
>     File "<string>", line 1, in ?
>   ImportError: no module named java

Based on some surfing, I realized that I need to supply more information. I 
am running on RedHat Linux RawHide 7.1.94, with the Sun Linux JDK 1.3.1_01. I 
can't find any way to turn off the JIT with this JVM; passing "-classic" to 
the JVM does not help. I'm running Java with the command --

  java -cp .:/opt/java/jython-2.1a1/jython.jar SimpleEmbedded

and, trying to add 'rt.jar' to the command line, as in --

  java -cp
      .:
      /opt/java/jdk/jdk1.3.1_01-i386-Linux/jre/lib/rt.jar:
      /opt/java/jython-2.1a1/jython.jar
    SimpleEmbedded

does not help. Peace,

Ihab

-- 
Ihab A.B. Awad <ih...@ah...>
Center for Computational Genomics and Bioinformatics,
University of Minnesota. http://www.cbc.umn.edu/~ihab/

[Jython-users] ImportError: no module named java

[Ihab A.B. A. <ih...@ah...>]

Hi there,

I'm having what must be a pretty simple newbie problem embedding Jython. I'm 
using Jython 2.1 Alpha 1. I can reproduce my problem by a 2-line change to 
the included "SimpleEmbeddedjava" example; when I add --

  interp.exec("import java.lang");
  interp.exec("print java.lang");

I get the error --

  Exception in thread "main" Traceback (innermost last):
    File "<string>", line 1, in ?
  ImportError: no module named java

What am I missing? What do I need to do? I tried to figure it out by reading 
the code of 'jython.java', since I can definitely "import java.lang" in an 
interactive console, but I couldn't.

Thanks and peace,

Ihab

-- 
Ihab A.B. Awad <ih...@ah...>
Center for Computational Genomics and Bioinformatics,
University of Minnesota. http://www.cbc.umn.edu/~ihab/

[Jython-users] manual installation

[dman <ds...@ri...>]

I want to use jython for a school project.  The project is to design
and build a mail client and will use Moshe Zadka's PMS framework.  I
will need to manually install jython into the project's directory
structure so that no configuration of the lab machines or the prof's
machine is necessary.

When I used Jython on windows, there was a Lib directory in the
directory I installed jython in.  This Lib directory contained many
.py files for the standard modules.  Now I am using Debian and have
installed the debian package (2.1-alpha3-3).  The
/usr/share/jython/Lib directory has very few .py files, and the
startup scripts include the CPython lib directory (/usr/lib/python2.0)
in the python.path system property.  This seems a little odd to me as
it will include many modules that depend on C libraries aas available
modules.  I checked the jython cvs repository (and the nightly
tarball) and found that the Jython Lib directory matches my debian
system.

For my manual setup, is it correct to simply copy the .py modules that
I need from CPython?  Have any of the mail modules been tested with
Jython?  (poplib, imaplib, smtplib, rfc822, the MIME modules)  For now
I have been copying the CPython modules (symlinking, really) until
importing the PMS package succeeded.  I am hoping I don't run into any
serious compatibility conflicts.

TIA,
-D

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**********

Re: [Jython-users] class conflict

[Chris G. <cg...@gc...>]

Hi Brian,

Thanks for your response.  Yes, this is the exact behavior that I'm 
seeing...  Your work-around that you provided in  your previous message 
works great, but I'd also be interested in knowing why it does not 
produce the expected results.

Chris

Brian Zhou wrote:
> Hi Chris,
> 
> I can reliably reproduce the problem.
> 
> $ lynx -dump http://localhost:8080/ctx/helloA.py
>    from pkgA import Foo; Foo() => pkgA.Foo()
>    pkgA.Foo() => pkgA.Foo()
> $ lynx -dump http://localhost:8080/ctx/helloB.py
>    from pkgB import Foo; Foo() => pkgB.Foo()
>    pkgB.Foo() => pkgB.Foo()
> $ lynx -dump http://localhost:8080/ctx/helloA.py
>    from pkgA import Foo; Foo() => pkgB.Foo()
>    pkgA.Foo() => pkgA.Foo()
> 
> The third request shows the problem, while pkgA.Foo() and pkgB.Foo() works
> fine.
> 
> I guess different servlet URLs share the same PyServlet instance, thus the
> same PythonInterpreter instance. JSP does not have this problem because it
> does not have separate python name space.
> 
> But even with the workaround, it still puzzles me, as the following is the
> expected result.
> 
> Jython 2.1a3 on java1.4.0-beta2 (JIT: null)
> Type "copyright", "credits" or "license" for more information.
> 
>>>>from pkgA import Foo
>>>>Foo()
>>>>
> pkgA.Foo()
> 
>>>>from pkgB import Foo
>>>>Foo()
>>>>
> pkgB.Foo()
> 
>>>>from pkgA import Foo
>>>>Foo()
>>>>
> pkgA.Foo()
> 
> -Brian
> 
> ----- Original Message -----
> From: "Chris Gokey" <cg...@gc...>
> To: <jyt...@li...>
> Cc: "Dave Kendig" <dk...@gc...>
> Sent: Friday, October 05, 2001 9:02 AM
> Subject: [Jython-users] class conflict
> 
> 
> 
>>Hi everyone,
>>
>>I'm seeing some strange behavior when running jython servlets from
>>Tomcat 4.  Not sure where the source of the error is but I'll try to
>>explain.
>>
>>I have 2 classes and they both have the same name but our in different
>>packages, ie., something like this:
>>
>>pkgA.Foo
>>pkgB.Foo
>>
>>These two classes are different implementation-wise, but they both have
>>the same name.
>>
>>The code I have very explicity refers to pkgA.Foo:
>>
>>from pkgA import Foo
>>f = Foo()
>>
>>but for some reaon it is using pkgB.Foo.
>>
>>Now, since this is all loaded under the Tomcat virtual machine, it it
>>possible that pkgA.Foo did get loaded into memory, so somehow maybe it
>>overwrote the pkgB.Foo when it was loaded by another application?
>>
>>I noticed this behavior because I was getting all kinds of errors when
>>the application was loading and executing the wrong Foo.  Then when I
>>restarted the Tomcat server everything worked fine.
>>
>>I'm wondering is it possible to explicitly use a class from a particular
>>package like this:
>>
>>str = java.lang.String()
>>
>>This can be done in Java, can this be done in python?
>>
>>Hopefully this makes some sense to someone :)
>>
>>Chris
>>
>>
>>
>>--
>>  __________________________________________________
>>/\
>>
>>           \
>>\_| Christopher D. Gokey, SSAI, NASA/GCMD          |
>>   | 18 Martin Road, Shelburne Falls, MA  01370     |
>>   | Phone: Voice (413) 625-8129 / FAX 208-248-9055 |
>>   | cg...@gc... / http://gcmd.nasa.gov    |
>>   | ICQ #52132386, AOL IM: chrisgokey              |
>>   |   _____________________________________________|_
>>    \_/______________________________________________/
>>
>>
>>_______________________________________________
>>Jython-users mailing list
>>Jyt...@li...
>>https://lists.sourceforge.net/lists/listinfo/jython-users
>>
>>



-- 
  __________________________________________________
/\ 
			 
	           \
\_| Christopher D. Gokey, SSAI, NASA/GCMD          |
   | 18 Martin Road, Shelburne Falls, MA  01370     |
   | Phone: Voice (413) 625-8129 / FAX 208-248-9055 |
   | cg...@gc... / http://gcmd.nasa.gov    |
   | ICQ #52132386, AOL IM: chrisgokey              |
   |   _____________________________________________|_
    \_/______________________________________________/

Re: [Jython-users] classloader funkiness when inheriting from java interfaces

[<Mat...@i2...>]

Cool, thanks for the workaround.  I guess I'll be the one doing the 
stressing =)

Matt

On 10/18/2001 08:21:28 PM jython-users-admin wrote:
> 
> Hi. It was a bug, now it's fixed in the CVS.
> Starting with jython 2.0 inheriting from java
> classes from 3rd-party classloaders is supported
> by design but has not really been stressed ;).

RE: [Jython-users] Creating a .class file from a .py file from in side a Java app

[Jim A. <Ji...@do...>]

For various reasons, I just use 'compile' directly:

PyCode compiledPage = __builtin__.compile(pythonCode, showThisOnError,
"exec");

Although I don't know if there's a way to 'optionally write out the .class'
?...


> -----Original Message-----
> From: Robert W. Bill [mailto:rb...@di...]
> Sent: Thursday, October 18, 2001 7:45 PM
> To: Max Muller
> Cc: jyt...@li...
> Subject: Re: [Jython-users] Creating a .class file from a .py 
> file from
> inside a Java app
> 
> 
> Hello Max,
> 
> On Thu, 18 Oct 2001, Max Muller wrote:
> > Hi,
> > 	I have actually just recently gotten into jython, very cool
> > I must say.  I am right now in the process of writing a WebObjects
> > framework that will allow for the use of Jython WOComponents.  When
> > it is done I'll release the source and make an annoucement on this
> > list.  Anyways, right now I have written a JythonClassLoader that
> > when given the path to a .py file it will compile the file to a
> > .class using jythonc and then read the .class in and construct the
> > Class object. So what I am wondering is it possible to not use
> > jythonc to compile the .class? I have been looking through 
> the api in
> > the compiler package, but I haven't been able to find that magic
> > method.  What I would really like to be able to do is in my Java app
> > read in the .py file and then using the Java api's of 
> jython, compile
> > the .py file into a byte array (optionally write out the .class at
> > this point) then construct the Class object, never having to fire up
> > a process outside the regular vm.  Anyone have any ideas?  Thanks in
> > advance.
> 
> An embedded interpreter sounds ideal for your situation, if I've
> understood everything correctly. You could execute a .py file in the
> embedded interpreter, then retrieve the class defined in that 
> file as a
> Java object with the interpreter's get method.  A good 
> example of this is
> the org.python.util.PyServlet class that comes with Jython.
> 
> More embedding info found at http://www.jython.org/docs/embedding.html
> 
> -robert
> 
> 
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> https://lists.sourceforge.net/lists/listinfo/jython-users
> 

[Jython-users] Re: instance already instantiated error

[Andres Corrada-E. <co...@ci...>]

Hello,

Please bear with me. I'm new to Jython and want to use Python code in Java
development environment. My attempt is failing because of a "instance
already instantiated" error. I've simplified the rand.py code in
www.jython.org to this:

from java.util import Random

class rand(Random):

    def __init__( self ):
        "@sig public rand()"

       # Random.__init__( self )


    def nextDouble( self ):
        return Random.nextDouble( self )

I can use jythonc to turn this into a java class which I then use from a
simple java file:

import rand;

class TestRand
{
    public static void main(String args[]){
	rand firstRand = new rand();
	System.out.println( firstRand.nextDouble() );
    }
}

As long as I do not call Random.__init__(self) in rand.__init__, the
procedure works. But if I uncomment the line it fails with the
"instance already instantiated" error. Since the actual Python class that
I want to create needs to have something like,
JavaSuperClass.__init__(self, foo)
this commenting out of the line is not going to work for me.

Any ideas on what I am doing wrong? I'm using Jython-2.0. on a SunOs
machine.

Andres Corrada-Emmanuel
Senior Research Fellow
Center for Intelligent Information Retrieval
University of Massachusetts, Amherst

Re: [Jython-users] Creating a .class file from a .py file from inside a Java app

[Robert W. B. <rb...@di...>]

Hello Max,

On Thu, 18 Oct 2001, Max Muller wrote:
> Hi,
> 	I have actually just recently gotten into jython, very cool
> I must say.  I am right now in the process of writing a WebObjects
> framework that will allow for the use of Jython WOComponents.  When
> it is done I'll release the source and make an annoucement on this
> list.  Anyways, right now I have written a JythonClassLoader that
> when given the path to a .py file it will compile the file to a
> .class using jythonc and then read the .class in and construct the
> Class object. So what I am wondering is it possible to not use
> jythonc to compile the .class? I have been looking through the api in
> the compiler package, but I haven't been able to find that magic
> method.  What I would really like to be able to do is in my Java app
> read in the .py file and then using the Java api's of jython, compile
> the .py file into a byte array (optionally write out the .class at
> this point) then construct the Class object, never having to fire up
> a process outside the regular vm.  Anyone have any ideas?  Thanks in
> advance.

An embedded interpreter sounds ideal for your situation, if I've
understood everything correctly. You could execute a .py file in the
embedded interpreter, then retrieve the class defined in that file as a
Java object with the interpreter's get method.  A good example of this is
the org.python.util.PyServlet class that comes with Jython.

More embedding info found at http://www.jython.org/docs/embedding.html

-robert

[Jython-users] Creating a .class file from a .py file from inside a Java app

[Max M. <max...@ma...>]

Hi,
	I have actually just recently gotten into jython, very cool  
I must say.  I am right now in the process of writing a WebObjects  
framework that will allow for the use of Jython WOComponents.  When  
it is done I'll release the source and make an annoucement on this  
list.  Anyways, right now I have written a JythonClassLoader that  
when given the path to a .py file it will compile the file to a  
.class using jythonc and then read the .class in and construct the  
Class object. So what I am wondering is it possible to not use  
jythonc to compile the .class? I have been looking through the api in  
the compiler package, but I haven't been able to find that magic  
method.  What I would really like to be able to do is in my Java app  
read in the .py file and then using the Java api's of jython, compile  
the .py file into a byte array (optionally write out the .class at  
this point) then construct the Class object, never having to fire up  
a process outside the regular vm.  Anyone have any ideas?  Thanks in  
advance.

Regards,	
	Max

ps - One thing that I did think of that just doesn't seem very  
efficient is to use the Interpreter and read in the main.py of the  
jythonc and try to catch the output before it goes to disk. But that  
sounds like it would have more overhead than just running a process  
outside the current process.

Re: [Jython-users] classloader funkiness when inheriting from java interfaces

[Samuele P. <pe...@in...>]

Hi. It was a bug, now it's fixed in the CVS.
Starting with jython 2.0 inheriting from java
classes from 3rd-party classloaders is supported
by design but has not really been stressed ;).

Patch:
Index: MakeProxies.java
===================================================================
RCS file: /cvsroot/jython/jython/org/python/core/MakeProxies.java,v
retrieving revision 2.16
retrieving revision 2.17
diff -C2 -d -r2.16 -r2.17
*** MakeProxies.java 2001/02/14 22:17:54 2.16
--- MakeProxies.java 2001/10/19 00:16:45 2.17
***************
*** 22,27 ****
              if (referent != null) {
                  secondary.insertElementAt(referent,0);
-                 referents = secondary;
              }
          } else {
              if (referent != null) {
--- 22,27 ----
              if (referent != null) {
                  secondary.insertElementAt(referent,0);
              }
+             referents = secondary;
          } else {
              if (referent != null) {

otherwise Workaround:

class Foo(java.lang.Object, Java3rdPClassLoaderInterface): pass
                ^
regards, Samuele Pedroni.

----- Original Message -----
From: <Mat...@i2...>
To: <jyt...@li...>
Sent: Friday, October 19, 2001 12:01 AM
Subject: [Jython-users] classloader funkiness when inheriting from java
interfaces


> I can use a custom classloader to load a Java class using a classpath
> other than that given jython at startup.  I can then define a new jython
> class deriving from that Java class, and use it without any problems.
> However, if I try and do the same thing with a Java exception, I get a
> java.lang.NoClassDefFoundError exception.  Anyone know why this is, or if
> there is a workaround?  I've provided an example below, just sub in values
> for classpath/classname and you will only see the error when classname is
> a java interface.
>
> from java.io import *
> from java.net import *
> from jarray import *
>
> # some.jar not in jython startup classpath
> classpath = ["some.jar"]
> classname = "some.class.in.some.jar"
>
> urls = array([File(each).toURL() for each in classpath], URL)
> classLoader = URLClassLoader(urls)
> javaClass = classLoader.loadClass(classname)
>
> class Foo(javaClass):
>     pass
>
> f = Foo()
>
> Any help appreciated, thanks,
>
> Matt
> mat...@i2...
>
>
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> https://lists.sourceforge.net/lists/listinfo/jython-users
>

Re: [Jython-users] classloader funkiness when inheriting from java interfaces

[<Mat...@i2...>]

On 10/18/2001 06:01:09 PM jython-users-admin wrote:
> 
> However, if I try and do the same thing with a Java exception, I get a

This should read interface instead of exception

Matt

[Jython-users] classloader funkiness when inheriting from java interfaces

[<Mat...@i2...>]

I can use a custom classloader to load a Java class using a classpath 
other than that given jython at startup.  I can then define a new jython 
class deriving from that Java class, and use it without any problems. 
However, if I try and do the same thing with a Java exception, I get a 
java.lang.NoClassDefFoundError exception.  Anyone know why this is, or if 
there is a workaround?  I've provided an example below, just sub in values 
for classpath/classname and you will only see the error when classname is 
a java interface.

from java.io import *
from java.net import *
from jarray import *

# some.jar not in jython startup classpath
classpath = ["some.jar"]
classname = "some.class.in.some.jar"

urls = array([File(each).toURL() for each in classpath], URL)
classLoader = URLClassLoader(urls)
javaClass = classLoader.loadClass(classname)

class Foo(javaClass):
    pass

f = Foo()

Any help appreciated, thanks,

Matt
mat...@i2...

[Jython-users] Pre-pub review of Jython book

[<Eli...@ne...>]

Hello Everyone!
I'm looking for people who would like to review a Jython book prior to its being published in order to evaluate its quality. If you're up to it, we might even ask for you to provide a quote that would be included in the book. For your participation I'll send you a couple of our books free of charge, you just have to pick 'em out.
If interested, please email me (eli...@ne...) within the next 48 hours and I'll provide you with the details.
Looking forward to hearing what you think of our book! :)

Elise Walter
Acquisitions Editor
New Riders Publishing

[Jython-users] instance already instantiated error

[Andres Corrada-E. <co...@ci...>]

Hello,

I'm new to jython. I'm having problems creating a java class from python.
I took the example in jython.org that subclasses java.util.Random into a
python class: rand. If I then use jythonc to turn "rand" into a rand.class
and use it in a java program I get an error with this traceback:

at org.python.core.Py.TypeError(Py.java, Compiled Code)
at org.python.core.PyReflectedConstructor.__call__(PyReflectedConstructor.java, Compiled Code)
at org.python.core.PyReflectedConstructor.__call__(PyReflectedConstructor.java, Compiled Code)
at org.python.core.PyReflectedConstructor.__call__(PyReflectedConstructor.java, Compiled Code)
at org.python.core.PyObject.__call__(PyObject.java, Compiled Code)
at rand$_PyInner.__init__$2(rand.java, Compiled Code)
at rand$_PyInner.call_function(rand.java, Compiled Code)
at org.python.core.PyTableCode.call(PyTableCode.java, Compiled Code)
at org.python.core.PyTableCode.call(PyTableCode.java, Compiled Code)
at org.python.core.PyTableCode.call(PyTableCode.java, Compiled Code)
at org.python.core.PyFunction.__call__(PyFunction.java, Compiled Code)
at org.python.core.PyInstance.__init__(PyInstance.java, Compiled Code)
at org.python.core.Py.initProxy(Py.java, Compiled Code)
at rand.<init>(rand.java, Compiled Code)
at TestRand.main(TestRand.java, Compiled Code)

Traceback (innermost last):
  File "~corrada/qa/test/rand.py", line 0, in __init__
TypeError: instance already instantiated for java.util.Random

The rand.py is as shown in www.jython.org/docs/subclassing.html

and my TestRand.java class looks like this:

import rand;

class TestRand
{
    public static void main(String args[]){
        rand firstRand = new rand();
        System.out.println( firstRand.nextDouble() );
    }
}

What am I doing wrong?

Andres Corrada-Emmanuel
Senior Research Fellow
Center for Intelligent Information Retrieval
University of Massachusetts, Amherst

Re: [Jython-users] Running a python script from java - help!

[dman <ds...@ri...>]

On Thu, Oct 18, 2001 at 11:58:23AM +0100, Shari Arman wrote:
| 
| This is probably a really soppy question but I'm very very very stuck...
| 
| 
| I'm trying to run a python script from a java GUI.  I have had to use
| jnios-1.7 to fix a problem I had with os.py, but now I'm getting:
| 	java.lang.UnsatisfiedLinkError: java.lang.UnsatisfiedLinkError: no
| posix in java.library.path
| 
| 
| I tried to compile jnios-1.7/*.cpp, but it is looking for io.h, does io.h
| even exist on UNIX??
| 	config.h:35: io.h: No such file or directory

Yes.  Do you have the *-dev packages installed?  I use Debian and have
the following :

---------
$ find /usr/include -name io.h -print
/usr/include/sys/io.h
/usr/include/asm/io.h

$ dpkg -S /usr/include/sys/io.h
libc6-dev: /usr/include/sys/io.h
---------

If you use debian, 'apt-get install libc6-dev' will fix that problem.

| Is there a precompiled unix version of posix.so that I can download??

I don't know of any, and 'apt-cache search' didn't turn up anything
that appears relevant.

HTH,
-D