jython-users — Discussion of and questions about using Jython

[Jython-users] Java 1.1 problems in CVS snapshop

[Kent J. <kjo...@tr...>]

I found two problems building the CVS snapshot of 20010310 under Java 1.1:

Module.java line 347:
Vector.toArray() is not in Java 1.1

I replaced
     private static final String[] emptyStringAr = new String[0];

     private String[] toNameAr(Vector names,boolean nullok) {
         int sz = names.size();
         if (sz ==0 && nullok) return null;
         return (String[])names.toArray(emptyStringAr);
     }

with

     private String[] toNameAr(Vector names,boolean nullok) {
         int sz = names.size();
         if (sz ==0 && nullok) return null;
         String[] nameArray = new String[sz];
         names.copyInto(nameArray);
         return nameArray;
     }


PyServlet.java line 75 and following:
Properties.setProperty(String, String) is not in Java 1.1, use 
Properties.put(Object, Object) instead.

I hope someone can make these changes in CVS, I don't have write access.

Kent Johnson                   Transparent Language, Inc.
kjo...@tr...       http://www.transparent.com

RE: [Jython-users] re: super newbie and newbie to newbie

[David S. <ds...@al...>]

> -----Original Message-----
> From: Robert W. Bill [mailto:rb...@di...]
> Sent: 10 March 2001 22:14

> Can other's help me out with a list a shells that provide serrogate
readlines?  
> Can anyone confirm Win2k? Yorick?

Yorick does not provide a shell.  But bundled with the UN*X version is a
utility based on gnu readline called rlterm.  You just do 'rlterm jython'
and command recall and emacs style editing is wrapped around your jython
session.

I use emacs shell mode.

Dave.

RE: [Jython-users] forget the last one; here's the real question

[Garcia, M. <mg...@Bu...>]

Hi Ben,
Your classpath also needs to have jython.jar in it which is where PyObject
resides.   Double check your jythonc script (assuming your on UNIX) is
pulling in the CLASSPATH env. variable too.

Mick

-----Original Message-----
From: Benjamin Collar
To: jyt...@li...
Sent: 3/9/01 7:30 PM
Subject: [Jython-users] forget the last one; here's the real question

allright, so i found out the problem last time was that i needed to add
the class to the package.

now i get this error:
java.lang.NoClassDefFoundError: org/python/core/PyObject

i was using:

jythonc -p org.tagents.examples --all --add org.python.core.PyObject
AgentPy.py

also I put /usr/local/java/extra/jython2.0/ in my classpath, but still
get
the above error :(. what to do?

thanks
ben


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RE: [Jython-users] DnD in Jython

[Ype K. <yk...@xs...>]

syKim,

you wrote:
>
>DnD is Drag & Drop which library in java.awt.dnd (over jdk1.2.x)
>
>>There is a file called treedemo.py in the Demo dir of the
> >jython installation: it will get you started.
>
>I already saw it.
>but, it's just Jtree demo not DnD..
>
>I don't know how do I handle that class as xxxListener, xxxRecognizer.

I have never programmed drag and drop. Still,
in case you have some (working) Java code I can help you converting
it to Jython. Could provide an example of Java DnD code
that you want to convert to Jython?

When you instantiate an object from a Java class in Jython, you actually
instantiate the object from a Jython proxy class.
You can pass keyword arguments
for this proxy to initialize its attributes/methods from.
This is how the "exit" works in the JTree example.
My guess is that you will need something similar for DnD events.

Regards,
Ype

RE: [Jython-users] DnD in Jython

[syKim <re...@ne...>]

Thank you for your regard, Ype

>What is DnD? Did I miss an important new acronym?

Sorry, my explain is too lack..

DnD is Drag & Drop which library in java.awt.dnd (over jdk1.2.x)

>There is a file called treedemo.py in the Demo dir of the
>jython installation: it will get you started.

I already saw it.

but, it's just Jtree demo not DnD..

I don't know how do I handle that class as xxxListener, xxxRecognizer.

syKim

Re: [Jython-users] Environment Variables

[John M. <joh...@ya...>]

Check this out.  I've had good luck with it.

http://sourceforge.net/projects/jnios/



--- Uncle Roastie <ro...@ro...> wrote:
> Python understands environment variables (os.environ).
> Java does not understand environment variables.
> 
> What does Jython do about environment variables?
> 
> Ron
> ron...@ne...
> ro...@ro...
> 
> 


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[Jython-users] Environment Variables

[Uncle R. <ro...@ro...>]

Python understands environment variables (os.environ).
Java does not understand environment variables.

What does Jython do about environment variables?

Ron
ron...@ne...
ro...@ro...

Re: [Jython-users] re: super newbie and newbie to newbie

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

Hello Vitaly,

On Sat, 10 Mar 2001, vitaly kupisk wrote:
> > so I've got these packages, and I want to import
> > classes from them. how do
> > i manage this?
>
> Your CLASSPATH has to have your .jar included, i.e.
> /whereverIkeepMyJavaClasses:/mystuff/myjavajars/TAgents.jar:whateverelse
>   (the directories (and jars) are separated by ":").
> If "jython" you type when you invoke jython is a shell
> script or a batch file you can set your CLASSPATH as a
> command line option. Then
> type "from org.tagents.examples import
> org.tagents.agents.*" at the prompt.
>
> Now my super newbie question, again (no responses last
> time).
>
> How do I get jython on Linux to remember the history
> of my commands and recall them with an "up" arrow key?
>  My bash and ksh shells do it, and python does it too.
>  Is there a history file I need to set up somewhere?

This is a common question.
I've added a faq entry (2.4) with the intent of helping people with this
and realized I'm short on information.  The jist is that readline provides
this functionality.  The original readline is in C so is not part of
Java/Jython.  There is experimental realine Java classes that will
eventually add this functionality, but not yet.  For now use a shell that
can wrap the running process (Jython) and allow readline behavior.

Here's the part I'm stuck on.  I live in emacs mostly, so I've never
really ventured beyond emacs' shell mode for this.  I tried Yorick's shell
with no luck even though I was told it works for this.  I've heard Win2k
shell may do this, but can't confirm this.  Can other's help me out with a
list a shells that provide serrogate readlines?  Can anyone confirm Win2k?
Yorick?  Other shells that we could list in the faq to help others out?

tnx,
Robert

Re: [Jython-users] DnD in Jython

[Ype K. <yk...@xs...>]

syKim,

you wrote:
>
>I'm recently trying  DnD programming of JTree in Jython..

What is DnD? Did I miss an important new acronym?

>but, It's too difficult to me -_- (I'm newbie yet..)
>
>I guess it's difference of programming style between jython and java..
>
>(especially, event driven like that xxListener, xxRecognizer etc.. )
>
>Who have DnD source that implement in Jython ?

There is a file called treedemo.py in the Demo dir of the
jython installation: it will get you started.

Have fun swinging,
Ype

[Jython-users] re: super newbie and newbie to newbie

[Ype K. <yk...@xs...>]

Vitaly,

you wrote:
<snip>
>
>How do I get jython on Linux to remember the history
>of my commands and recall them with an "up" arrow key?
> My bash and ksh shells do it, and python does it too.
> Is there a history file I need to set up somewhere?

Console.py in the Demo dir in the jython installation
will let you "up" and "down". It does not use a file for
history, but that would indeed be a very nice extension.

In case you think that's a hint: it is.

Have fun,
Ype

Re: [Jython-users] jython to java?

[Ype K. <yk...@xs...>]

John,

you wrote:
<snip>
>
>I've been looking for something like python for years.  It's the best!
>I finally have a medium in which I can express my algorithms.
>
>But...  As I heard years ago and still agree with, it's not the tool
>but the person that champions the tool.  I'm afraid I'm currently not
>in a good position in my current group to champion Python.  Over the
>years I've noticed a pattern.  New tribes arrive on the scene and
>wrestle with the presiding regime for power.  It's not enough to show
>up and do good work in order to lead us in a new direction.
>Consistently, the new groups actually has little to offer beyond their
>self marketing and soon must resort to bashing the old group in a
>desperate attempt to gain favor with the mother & father figures.

It's unusual to see things like bashing around python/jython.
They don't need it.

>Well, I guess that's politics and can be expected.  But, having made
>the "mistake" of actually produced working software in the past I am
>now a target.  If I say it's white then the reply is often that it's
>black.  Ugh.  The tide will turn but slowly.  In the meantime I am
>ridiculed for trying Python.
>
>Is there a lesson here for those who would like to see Python/Jython
>become mainstream?  Certain religions have clauses requiring members to
>pass the word.  It's lead to nasty conflicts but who can argue with
>their numbers.  And then there's the tobacco companies...

Iirc, you work in a Java environment. As long as you're allowed to
put jython.jar on the class path, and you are willing to write a tiny
bit of code to allow embedded jython scripting, you can use Jython
where you see fit.
Popular areas are:
- exploring Java API's interactively,
- testing,
- prototyping.
Before long you'll hit one of these. Remember how Linux is getting popular?

<snip>
>...  I highlighted the chart that I
>interpreted to say that Python is the *best* choice for productivity.
>It was the only thing pinned to my cube wall.  Alas, there was a flaw
>in my thinking that young rogue programmers (excuse me, anal ists with
>advanced degrees) can be taught anything based on objective research. 

People are primarily based on habits, and it is a personal investment
to get familiar with a new programming language.
 
From Java to Jython is quite straightforward as
Jython is almost readable when you know Java. Just
shake off the type checking mood introduced by the Java compiler,
bite through one or two syntax quirks, and productivity is there.
(Perhaps I am a bit overoptimistic, but if they have
advanced degrees, who knows?)
Then start writing adapters in two or three lines, instead of
in two or three classes/interfaces, and you're sold for the rest
of your career.
And then you have only just begun:
- change a GUI within 20 seconds for prototyping,
- from threading import WhatYouNeed, instead of Java synchronized/notify/wait.
- implement a state pattern by simply reassigning methods,

Have fun,
Ype

[Jython-users] DnD in Jython

[syKim <re...@ne...>]

Hello.. 

I'm recently trying  DnD programming of JTree in Jython..

but, It's too difficult to me -_- (I'm newbie yet..)

I guess it's difference of programming style between jython and java.. 

(especially, event driven like that xxListener, xxRecognizer etc.. )

Who have DnD source that implement in Jython ?

Please Help me..

syKim. 

[Jython-users] re: super newbie and newbie to newbie

[vitaly k. <try...@ya...>]

> so I've got these packages, and I want to import
> classes from them. how do
> i manage this?

Your CLASSPATH has to have your .jar included, i.e.
/whereverIkeepMyJavaClasses:/mystuff/myjavajars/TAgents.jar:whateverelse
  (the directories (and jars) are separated by ":"). 
If "jython" you type when you invoke jython is a shell
script or a batch file you can set your CLASSPATH as a
command line option. Then
type "from org.tagents.examples import
org.tagents.agents.*" at the prompt.

Now my super newbie question, again (no responses last
time).

How do I get jython on Linux to remember the history
of my commands and recall them with an "up" arrow key?
 My bash and ksh shells do it, and python does it too.
 Is there a history file I need to set up somewhere?

Thanks

Vitaly




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Re: [Jython-users] Lisp-Python

[George H. <ghe...@cf...>]

Gottfried F. Zojer wrote:

> 
> Maybe a OT questions.I saw a nice story in a german
> programmer-magazine about genetic programming.
> But everything is Lisp.Does anybody know a reference
> howto use Python for genetic programming or any
> form of Lisp or prolog integration.

There is a java implementation of prolog called javalog at

   http://www.exa.unicen.edu.ar/~azunino/

Presumably this could be used with jython. I've never tried that and 
only have taken a rudimentary look at javalog, so I really can't say 
much about how practical this is.  Hmmm, prolog in java under jython ... 
sounds like a real screamer to me!!!! ;-)

George

Re: [Jython-users] jython to java?

[John M. <joh...@ya...>]

--- Samuele Pedroni <pe...@in...> wrote:
> Hi.
> 
> A) Some general considerations
> 
> [John Mudd]
> > Maybe there's a market for this sort of scenario.  Use a subset of
> > Jython in exchange for the ability to switch to Java after the
> > prototype solidifies.  Maybe both languages would benfit from
> > collaboration.
> As philosophy (unrelated to java) that's the niche (at least in term
> of 
> promises) of Common Lisp System vendors, which still give a lot
> of dynamism in the delivered version, and the pontential niche
> of dylan (that didn't catch up), where you lose most of the dynamism
> for performance in the delivered version of a program, but you
> have full dynamism during development.

----snip----

Thanks for the detailed explanation.  On one hand it's a bit
intimidating for me.  I tend to oversimplify problems.  But, OTOH, it
is encouraging that others have already seen and tried to scale the
same mountain.  I trust that given enough time someone will surely make
it to the top.


> 
> 1) and using a bit of 4) as an idea has been around for a long time,
> let see if and what will happen with P3K.
> 

P3K?  I had no idea.  My expectations are now officially running
wild...

---snip-----

> 
> regards, Samuele Pedroni.
> 


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Re: [Jython-users] jython to java?

[John M. <joh...@ya...>]

--- D-Man <ds...@ri...> wrote:
> On Fri, Mar 09, 2001 at 06:40:38AM -0800, John Mudd wrote:
---snip---
> 
> Since you wrote this in Python to start with I'll assume you like
> python and are convinced of its merits.  It would probably be
> advantageous for you to determine why your group is pushing for Java.
> If it is because of simpler coding, portability, etc, then maybe you
> could present Python as an alternative.  If you can manage to get
> Python bindings for your CORBA orb that would help as well.  (BTW,
> ORBit has Python bindings,  it's the free open source orb that GNOME
> uses)

I've been looking for something like python for years.  It's the best! 
I finally have a medium in which I can express my algorithms.

But...  As I heard years ago and still agree with, it's not the tool
but the person that champions the tool.  I'm afraid I'm currently not
in a good position in my current group to champion Python.  Over the
years I've noticed a pattern.  New tribes arrive on the scene and
wrestle with the presiding regime for power.  It's not enough to show
up and do good work in order to lead us in a new direction. 
Consistently, the new groups actually has little to offer beyond their
self marketing and soon must resort to bashing the old group in a
desperate attempt to gain favor with the mother & father figures. 
Well, I guess that's politics and can be expected.  But, having made
the "mistake" of actually produced working software in the past I am
now a target.  If I say it's white then the reply is often that it's
black.  Ugh.  The tide will turn but slowly.  In the meantime I am
ridiculed for trying Python.

Is there a lesson here for those who would like to see Python/Jython
become mainstream?  Certain religions have clauses requiring members to
pass the word.  It's lead to nasty conflicts but who can argue with
their numbers.  And then there's the tobacco companies...


---snip---
> 
> I don't know very much about the 286's architecture other than it is

Me either.  I think the big flaw was a bizzare memory mapping scheme.

---snip--- 
> 
> If you want to read a good article comparing several languages and
> their performance vs. code size, check IEEE Computer magazine from a
> few months ago.  It compared C, C++, Java, Python, Perl, Tcl, and
> Rexx.

Good suggestion as I've already got it.  I highlighted the chart that I
interpreted to say that Python is the *best* choice for productivity. 
It was the only thing pinned to my cube wall.  Alas, there was a flaw
in my thinking that young rogue programmers (excuse me, anal ists with
advanced degrees) can be taught anything based on objective research.  


---snip---
> but writting Java extensions to Jython seems to be extremely easy.

*Agreed!*

---snip---

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Re: [Jython-users] Lisp-Python

[L. H. <hu...@ha...>]

Gottfried F. Zojer wrote:

> Hi Jython users,
> 
> Maybe a OT questions.I saw a nice story in a german
> programmer-magazine about genetic programming.

There are someone working on genetic programming in Python, but I don't 
know, who.

> But everything is Lisp.Does anybody know a reference
> howto use Python for genetic programming or any
> form of Lisp or prolog integration.

You may take a look at:

Denys Duchier
Continuations Made Simple and Illustrated

2000, Februar

http://www.ps.uni-sb.de/~duchier/python/continuations.html

> Thanks
Please gime the location of the mentioned article (;-


	Ludger

[Jython-users] Lisp-Python

[<go...@ya...>]

Hi Jython users,

Maybe a OT questions.I saw a nice story in a german
programmer-magazine about genetic programming.
But everything is Lisp.Does anybody know a reference
howto use Python for genetic programming or any
form of Lisp or prolog integration.

Thanks

Gottfried F. Zojer 

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Re: [Jython-users] Jython and CGI

[John H. <jo...@ne...>]

Venkatesh,
    Thanks for the speedy reply! I am using env in the she-bang. I'm running
Solaris 2.5.1. What platform were you on?
John

Venkatesh Prasad Ranganath wrote:

> Hi,
>
> The last time I tried to use jython for cgi I got a similar error.  This is
> because jython is a shell script and so use #!env jython as the first line of
> the script for it to be executed by jython.
>
>  - Venkatesh

[Jython-users] forget the last one; here's the real question

[Benjamin C. <bc...@cs...>]

allright, so i found out the problem last time was that i needed to add
the class to the package.

now i get this error:
java.lang.NoClassDefFoundError: org/python/core/PyObject

i was using:

jythonc -p org.tagents.examples --all --add org.python.core.PyObject
AgentPy.py

also I put /usr/local/java/extra/jython2.0/ in my classpath, but still get
the above error :(. what to do?

thanks
ben

Re: [Jython-users] Strange syntax errors in lib on Mac

[Frode R. <fro...@er...>]

Hi Kent,

This is because a bug in MRJ. Some time it return wrong number of byte read
from the file. Finn have add a workaround to the CVS version. I have not get
time to test the CVS version. I have made my own hack on Jython 2.0 to be
able to run it. Are you not able to run the CVS version send me a mail and I
can send you my hack.
-- 
/Frode Reinsnes


> Hello,
> 
> I am experimenting with jython 2.0 on MacOS and I am getting some
> very strange syntax errors in the supplied Python library. For
> example:
> 
>>>>  import codecs
> Traceback (innermost last):
>  File "<console>", line 1, in ?
>  File "/Heron/Applications/jython-2.0/Lib/codecs.py", line 396
> SyntaxError: Lexical error at line 396, column 41.  Encountered:
> <EOF> after : ""
> 
>>>>  import httplib
> Traceback (innermost last):
>  File "<console>", line 1, in ?
>  File "/Heron/Applications/jython-2.0/Lib/httplib.py", line 580
> SyntaxError: invalid syntax
> 
> Looking at the indicated lines they look fine to me. For example the
> error in codecs.py is in the middle of a long doc comment. If I try
> to delete the offending line in httplib the error moves to another
> line.
> 
> I am perplexed; I don't know if this is a Mac-related problem or
> what. Any help in tracking this down would be appreciated.
> 
> Thanks,
> 
> Kent Johnson                   Transparent Language, Inc.
> kjo...@tr...       http://www.transparent.com
> 
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> http://lists.sourceforge.net/lists/listinfo/jython-users
> 

[Jython-users] Strange syntax errors in lib on Mac

[Kent J. <kjo...@tr...>]

Hello,

I am experimenting with jython 2.0 on MacOS and I am getting some 
very strange syntax errors in the supplied Python library. For 
example:

>>>  import codecs
Traceback (innermost last):
   File "<console>", line 1, in ?
   File "/Heron/Applications/jython-2.0/Lib/codecs.py", line 396
SyntaxError: Lexical error at line 396, column 41.  Encountered: 
<EOF> after : ""

>>>  import httplib
Traceback (innermost last):
   File "<console>", line 1, in ?
   File "/Heron/Applications/jython-2.0/Lib/httplib.py", line 580
SyntaxError: invalid syntax

Looking at the indicated lines they look fine to me. For example the 
error in codecs.py is in the middle of a long doc comment. If I try 
to delete the offending line in httplib the error moves to another 
line.

I am perplexed; I don't know if this is a Mac-related problem or 
what. Any help in tracking this down would be appreciated.

Thanks,

Kent Johnson                   Transparent Language, Inc.
kjo...@tr...       http://www.transparent.com

RE: [Jython-users] super newbie question

[Benjamin C. <bc...@cs...>]

thank you Jeff, that did work dandy.

but now a different problem; perhaps you or someone can help me with it.
i used jythonc to turn the class into a .class and put it in a directory
that has some other .class examples for the system I'm using. I then used
ant to build the examples.jar file, and that class was apparantly included
(I say apparantly because the `sum` of examples.jar was different when i
had the file in question in that directory). but the following happens:

createAgent org.tagents.examples.AgentEx1 ===> works fine
createAgent org.tagents.examples.AgentPy ====> gives the following:

(a short note: I see that the code i'm using defines its own class
loader; I understand that that could be the problem. I just thought I
would check to see if I'm missing anything on the jython side before
pursuing that route)

java.lang.NoClassDefFoundError: org/tagents/examples/AgentPy (wrong
name: AgentPy)
        at java.lang.ClassLoader.defineClass0(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:496)
        at
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:11
7)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:251)
        at java.net.URLClassLoader.access$300(URLClassLoader.java:69)
        at
java.net.URLClassLoader$ClassFinder.run(URLClassLoader.java:544)        at
java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:203)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:325)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:380)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:257)
        at java.lang.ClassLoader.findSystemClass(ClassLoader.java:630)
        at
org.tagents.platform.AgentClassLoader.loadClass(AgentClassLoader.java
:94)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:257)

Thanks!
Ben

 On Fri, 9 Mar 2001, Jeff Davies wrote:

> In jython, try the following:
> 
> from org.tagents.agents import *
> 
> That should do the trick. Of course, these classes still need to be in your
> CLASSPATH for jython to find them.
> 
> - Jeff Davies
> 
> -----Original Message-----
> From: Benjamin Collar [mailto:bc...@cs...]
> Sent: Friday, March 09, 2001 11:24 AM
> To: jyt...@li...
> Subject: [Jython-users] super newbie question
> 
> 
> hi there
> 
> so I've got these packages, and I want to import classes from them. how do
> i manage this?
> 
> an example. the java source file Agent has this at the top:
> 
> package org.tagents.examples;
> 
> import org.tagents.agents.*;  
> 
> from jython, i tried "import org.tagents.agents.*," "import TAgents" (the
> jar file name), "import TAgents.jar", and so on, but nothing works. so how
> do I import this stuff?
> 
> thanks
> ben
> 
> 
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> http://lists.sourceforge.net/lists/listinfo/jython-users
> 

Re: [Jython-users] Jython and CGI

[Venkatesh P. R. <rvp...@ci...>]

Hi,

The last time I tried to use jython for cgi I got a similar error.  This is
because jython is a shell script and so use #!env jython as the first line of
the script for it to be executed by jython.

 - Venkatesh

[Jython-users] Jython and CGI

[John H. <jo...@ne...>]

All,
    I'm trying to run a CGI written in Jython. I got a test script
working in regular python first and then changed it to jython. The
jython version didn't work.
    After poking around I discovered that the os.envron variable was
empty. Presumably this is why FieldStorage is empty as well. Is there a
good way to get the environment variables into a jython script?
John