jython-dev — Discussion of developing and enhancing Jython itself(!) (not how to use Jython)

[Jython-dev] Help

[Stephen F. <ste...@ea...>]

My job requires me to write automated
test sequences.

I believe they plan to use Jython for
this purpose.

I can read scripts okay.  They make sense.

I am ignorant of (but not limited to )
the following:

Java
Java script
Java beans
Java anything
Python
Jython
JPython

I just need some starting point lower
than what I have seen
on Jython.org

Thanks
Stephen Fay
Jython dummy

[Jython-dev] Null pointer exception in Demo/embed/SimpleEmbedded...

[Jayson S B. <js...@ci...>]

Hiho,

   I'm a developer who is trying to embed Python code into Java, so of
course I came to Jython. When trying to run your example after compiling,
I get the following stack dump:
  Exception in thread "main" java.lang.NullPointerException
   at org.python.core.PyJavaClass.lookup(PyJavaClass.java:39)
   at org.python.core.PyObject.<init>(PyObject.java:46)
   at org.python.core.PySingleton.<init>(PySingleton.java:8)
   at org.python.core.PyNone.<init>(PyNone.java:7)
   at org.python.core.PySystemState.initStaticFields(PySystemState.java:341)
   at org.python.core.PySystemState.initialize(PySystemState.java:320)
   at org.python.core.PySystemState.initialize(PySystemState.java:294)
   at org.python.core.PySystemState.initialize(PySystemState.java:287)
   at org.python.util.PythonInterpreter.<init>(PythonInterpreter.java:61)
   at org.python.util.PythonInterpreter.<init>(PythonInterpreter.java:45)
   at SimpleEmbedded.main(SimpleEmbedded.java:6)

Any idea what's causing this? no one has mentioned it in the FAQ's or the
list archives...

Jayson Baird
js...@ci...

[Jython-dev] Jython papers

[Udo K. <ud...@gm...>]

Hello,

my name is Udo Kleinkop. I'm a CS student at the TU Braunschweig,
Germany. At the moment I'm writing my dissertation about scripting
languages in database applications. One chapter will probably be the
use of Jython in Java framework for DB applications.

Do you have free available papers about the internal design of the Jython
interpreter? It would help me a lot to get a 'jump start' into Jython.

Regards
Udo Kleinkop

[Jython-dev] could not run applet

[Melissa M. <mel...@mo...>]

I could not load any of the demo applets.  I do not have jython
installated on my PC.  Here is the information you required.

1.What OS (name and version) and Browser (name and version) you are
running
    Windows 2000
    Netscape Communicator 4.61

2.A copy of your Java console window after failing to run an applet
    #Applet exception: class HelloWorld could not be loaded

3.The URL of the applet that didn't work for you
    http://www.jython.org/applets/index.html

Regards,
Melissa

[Jython-dev] FAQ change about java classes reloading

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

For information:

I have changed FAQ entry about java classes reloading
in order to reflect current status (= "jreload" module).

regards, Samuele Pedroni.

Re: [Jython-dev] problems with applets

[<bc...@wo...>]

[salvatore.didio]

>Why does I have to reload my page to view an applet?; Is there a way to =
>load
>the applet at the first aperture of the page ?

Normally the applet is shown when loaded, including the first time. 

A common problem is described on 

   http://www.jython.org/docs/jythonc.html

"""
Note:One special thing to consider when building applets is the java VM
version used when compiling the sources must usually be the same as the
VM version used by the browser. If a newer JVM is used when compiling
the applets, the compiled code may have references to classes that does
not exists in older JVM's.
"""

For further help, you will have to open the java console and tell us
what messages there are shown. When using MS-IE 5.0 you may have to
enable the java console like this:

- Menu "Tools\Internet options"
- Folder tab "Advanced"
- Checkbox "Java console enabled" must be marked.

The java console can be opened from 

- Menu "View\Java console".

regards,
finn

RE: [Jython-dev] Applet & MS explorer problem..

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

I compiled the applet under jdk1.1.8..

It works so well in MS explorer.

But, jdk1.1.8 has so many constraint for swing and so on..

Don't you have another way for jdk1.2.x or jdk1.3.0

RE: [Jython-dev] Applet & MS explorer problem..

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

>You can try to open the java console to see the actual error message. On
>my version of MSIE it is under the View\Java Console menu.

>When I run the applet I will get a "com.ms.security.SecurityExceptionEx:
>Unable to access system properties." which is OK.

I tried to open java console but, I don't know where it is.

when I opened applet in java hompage. it run automatically.

but, it's just in java hompage example. (I set the plug-in in control panel
for java console)

And, I suddenly think up reload..

I showed "hello world!!" in explorer at last.. :)

but, It's nessary reloading.

When applet first loaded in explorer and bring up the mouse cursor on
applet,

the error message is "

load: HelloApplet can't be instantiated"

What can I do something for it? (for show applet when it's first loaded)

>I'm guessing that you compiled the applet while running jdk1.3. That
>does not work. You will have to use a jdk1.1 when compiling the applet.

>If I compile an applet with jdk1.3 and run it in MSIE, I get a

>  com.ms.security.SecurityExceptionEx: java.io.IOException: bad path:
>  ...java\awt\event\HierarchyEvent.class

>in the MSIE java console.

Ok After I test it, I announce to you the result.

>PS. Is there anything you can do to avoid sending mails as raw base64.
>This is what your mail looks like in my mail program. I have to go
>through some manual work in order to read the actual text:

I'm sorry, that is my outlook's default. now, I changed it.

Happy python  :)

: syKim

[Jython-dev] PyServlet

[<bc...@wo...>]

[In a private conversation David Syer raised several good points about
PyServlet. Forgive me for taking the private discussion to the list]

>You could add getServletContext().getRealPath("/") to sys.path in PyServlet
>in the constructor.

A good idea. That should take care of most issues with the application
part of sys.path.

In addition to this, I suggest that we add a fake __file__ attribute to
the globals before loading the .py file and before calling the service()
method. That way the main .py will know where it is located during load.

>Does [the fact sys.prefix is null in PyServlet] explain why the cachedir
>is created in a weird place (the web-apps directory, not <path-to-jython.jar>)?

Exactly.

I've already added the init-params as jython options, so we in web.xml
can do:

 *         <init-param>
 *             <param-name>python.home</param-name>
 *             <param-value>/usr/home/jython-2.0</param-value>
 *         </init-param>

to set python.home and all the other registry properties. Unfortunately
this is mostly useless if we want to set a path to something relative to
the webapps folder. And most of the times, that is exactly what we want.

So I suggest that unless a specific python.home is set in init-param or
System.getProperties(), PyServlet will set python.home to
<context>/WEB-INF/lib. This means the jython.jar, the registry file and
the ./Lib directory can be distributed in WEB-INF/lib.

regards,
finn

Re: [Jython-dev] Jython 2.0

[<bc...@wo...>]

[Stevenson Hickey]

>I tried to download Jython 2.0 and got to the download page, clicked on =
>Download and was taken to a page that led me to license, installation =
>instructions, and a file that was called a .class file.
>
>I do not know what to do with this file.

You will have to execute the jython-20.class files from a "DOS box" as
described on the install page:

  http://www.jython.org/install.html

>My windows 98 seems to think that it is a MUSIC file.

That is OK. What windows think only matter if you double-click on a
file, and I would *not* expect that to work in most cases. Instead you
will have to type one of the three command lines listed on the
installation page.

>Have you made a mistake?

I've made tons of mistakes <wink>, but not yet on this topic.

regards,
finn

Re: [Jython-dev] Re: [Jython-users] classpath questions

[<bc...@wo...>]

[Samuele]

>Hi.
>
>[Finn on jython-users]
>> Remember that we are parsing the CLASSPATH value with code like:
>>
>>         for (int i = 0; i < paths.__len__(); i++) {
>>             String entry = paths.get(i).toString();
>>             if (entry.endsWith(".jar") || entry.endsWith(".zip")) {
>>                 addJarToPackages(new File(entry),true);
>>
>When I worked around that I noticed the case-sensivity problem, but given there
>were no bug-reports
>complaints on it, I just forgot.
>
>Should we change that (and similar code) for accepting ".JAR" and ".ZIP" too?

Yes, we migth as well. Also .Jar and .zIP and ...

regards,
finn

Re: [Jython-dev] Applet & MS explorer problem..

[<bc...@wo...>]

[syKim]

>I'm begginer for jython..
>
>I want to run some applet under MS explorer.
>
>I tested simple code like that :
>
>## HelloApplet.py
>import java
>class HelloApplet(java.applet.Applet):
>    def paint(self,g):
>        "@sig public void paint(java.awt.Graphics g)"
>        g.drawString ("Hello World!",50,25)

>HTML code :
><html><body>
><applet code=HelloApplet.class archive=HelloApplet.jar width=200 height=300>
></applet>
></body></html>
>
>It works under both appletviewer & netscape..
>
>but, It doesn't work under MS explorer..

You can try to open the java console to see the actual error message. On
my version of MSIE it is under the View\Java Console menu.

When I run the applet I will get a "com.ms.security.SecurityExceptionEx:
Unable to access system properties." which is OK. 

>What can I do something for solveing this problem?
>
>(I guess that plug-in's problem..)
>
>my enviroment :
>
>windows ME
>jdk1.3.0_01
>jre 1.3.0
>jython 2.0

I'm guessing that you compiled the applet while running jdk1.3. That
does not work. You will have to use a jdk1.1 when compiling the applet.

If I compile an applet with jdk1.3 and run it in MSIE, I get a

  com.ms.security.SecurityExceptionEx: java.io.IOException: bad path:
  ...java\awt\event\HierarchyEvent.class

in the MSIE java console.

regards,
finn

PS. Is there anything you can do to avoid sending mails as raw base64.
This is what your mail looks like in my mail program. I have to go
through some manual work in order to read the actual text:

To: "Jython-Dev" <jyt...@li...>
Subject: [Jython-dev] Applet & MS explorer problem..
From: "syKim" <re...@ne...>
Date: Sat, 3 Feb 2001 13:30:34 +0900

SSdtIGJlZ2dpbmVyIGZvciBqeXRob24uLg0KDQpJIHdhbnQgdG8gcnVuIHNvbWUgYXBwbGV0IHVu
ZGVyIE1TIGV4cGxvcmVyLg0KDQpJIHRlc3RlZCBzaW1wbGUgY29kZSBsaWtlIHRoYXQgOg0KDQoj
IyBIZWxsb0FwcGxldC5weQ0KaW1wb3J0IGphdmENCmNsYXNzIEhlbGxvQXBwbGV0KGphdmEuYXBw
bGV0LkFwcGxldCk6DQogICAgZGVmIHBhaW50KHNlbGYsZyk6DQogICAgICAgICJAc2lnIHB1Ymxp
YyB2b2lkIHBhaW50KGphdmEuYXd0LkdyYXBoaWNzIGcpIg0KICAgICAgICBnLmRyYXdTdHJpbmcg
...

RE: [Jython-dev] Jython console under Tru64 Unix

[Adam B. <ada...@gb...>]

Bock Finn proscribed:

> [Adam Burke]
> 
> >Odd problem.  Jython console started with no parameters fails with an
> >"IOError - File not found -".  However the problem goes away when the
> >interpreter is started with a script param or started with the -v =
> >option.
> >
> >Compaq Tru64 Unix
> >uname -a
> >OSF1 supanova V4.0 1229 alpha=20
> >
> 
	<slash>

> The generated script use "$@" to pass the script arguments to java. If
> no arguments are supplied, perhaps Tru64 will pass it as "". Try to
> change the "jython" script to use some other way of passing the args:
> 
>   java .... org.python.util.jython $1 $2 $3 $4 $5
> 
> This is too naive for production use, but I think it can help illustrate
> where the problem is. Changing the shell in the first line of the script
> might also help.
> 
Doh!  /bin/sh has issues on (at least our) installations of Tru64, I've been
running into them for other utilities as well, I should have picked that.
Using #!/bin/ksh fixes it.

Thanks.

Adam

[Jython-dev] problems with applets

[salvatore.didio <sal...@wa...>]

Hello,

Why does I have to reload my page to view an applet?; Is there a way to =
load
the applet at the first aperture of the page ?

Thanks

Re: [Jython-dev] stringbuffer.py

[<bc...@wo...>]

[Ype Kingma]

>I'll take a look at tje UserString.MutableString class.
>I've been wondering about the difference between a normal module
>and a standard module, 

Probably sloppy word usage on my part, but by "standard modules" I meant
the modules that are distributed with Jython.

Technically there are no difference.

>>The last count method will validate the start/end indexes so the
>>sys.maxint trick also works.
>
>I guess the trick is to move the real work to the java side as
>much as possible.

Yes.

>A good reason to upgrade. Is there a good reason to go beyond 2.0
>at this moment?

The NEWS from CVS contains:

xx-xxx-2001 Jython 2.1 alpha 1

  New features.
   - Improve speed when indexing a string and iterating over a string
     in a for loop.
   - Reworked coercing model (pep-0208)
   - Added {}.popitem().
   - Improved speed for python files by buffering the RandomAccessFile.
   - Added function attributes (pep-0232)
   - Rich comparison (pep-0207)
   - Updated cPickle to handle CPython compatible unicode strings.
   - Updated sre to CPython-2.1a1
   - Added the "new" module

  Bug fixes.
   - Allow self referencing adapters to be collected when using weak
     tables.
   - Added workaround for a reader bug in MRJ22Jitc.01.


regards,
finn

Re: [Jython-dev] Jython 2.0

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

Hi Stevenson,

On Sat, 3 Feb 2001, Stevenson Hickey wrote:
> HI!
>
> I tried to download Jython 2.0 and got to the download page, clicked on
> Download and was taken to a page that led me to license, installation
> instructions, and a file that was called a .class file.

So far, so good.

> I do not know what to do with this file.  My windows 98 seems to think
> that it is a MUSIC file.

I have no idea what kind of music file has a .class extension.
Remove it in view:folder options:file types if it gets annoying, but that
is not the problem here.

Visit http://jython.sourceforge.net/install.html for install instructions.
The Cliff notes are...

type:

	java -cp . jython-20

in a dos window, while in the directory that the downloaded
jython-20.class file is located.

If you run into troubles, revisit the install page noted above or check
out section 2 of the FAQ at:

	jython-20 http://www.jython.org/cgi-bin/faqw.py?req=index

If you still have difficulties, post to
jyt...@li....  It's nothing official, but "dev"
lists are normally reserved for development "of" something as opposed to
development "with" something- development of Jython itself as opposed to
programming with it in this case.

Best of luck.

Regards,
-Robert

[Jython-dev] Jython 2.0

[Stevenson H. <st_...@ho...>]

HI!

I tried to download Jython 2.0 and got to the download page, clicked on =
Download and was taken to a page that led me to license, installation =
instructions, and a file that was called a .class file.

I do not know what to do with this file.  My windows 98 seems to think =
that it is a MUSIC file.

Have you made a mistake?

Sincerely,

Stevenson Hickey

[Jython-dev] Re: [Jython-users] classpath questions

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

Hi.

[Finn on jython-users]
> Remember that we are parsing the CLASSPATH value with code like:
>
>         for (int i = 0; i < paths.__len__(); i++) {
>             String entry = paths.get(i).toString();
>             if (entry.endsWith(".jar") || entry.endsWith(".zip")) {
>                 addJarToPackages(new File(entry),true);
>
When I worked around that I noticed the case-sensivity problem, but given there
were no bug-reports
complaints on it, I just forgot.

Should we change that (and similar code) for accepting ".JAR" and ".ZIP" too?

regards, Samuele Pedroni.

[Jython-dev] I plan to use Jython for a ******* GAME *********

[Zac J. <Cyb...@ho...>]

Okay, I'm going to be working on a game here, it's currently under
development and I put updates on http://webmud.8m.com/  that displays the
current status of the Applet.  Anyhow, I plan to use instances of Jython
interp's in each complex object in the game, however, I don't want it to
take a ton of memory, any suggestions on how to slim down the jython and
recompile to get the most for my megabyte?  I really don't need a lot of
python support, most operations will be implemented in my java applet, but,
referenceable from the jython script for post compilation customization.

_Cy...@ho...

Re: [Jython-dev] Newbie on jython

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

On Sat, 3 Feb 2001, Syver Enstad wrote:

> Hi!
>
> I am contacting you to find what forums are the best to use when being a
> total newbie on jython and java. Should I use the comp.lang.python group
> or are there other forums that are more appopriate for jython questions.

jyt...@li... is a great venue for these questions.

> I've been using cpython for about half a year and find it really
> excellent, I thought that jython would be a good entrance into the java
> world, and it seems to be.
>
> I have a couple of questions that should be directed to the proper
> forum, but state them here anyway, if someone has the time too enlighten
> me.
>
> There's a couple of things that I don't get yet. How can I compile a .py
> file into a java .class? I've read the documentation on this, but there
> seems to be something I am doing wrong. When trying to compile the .py
> file the javac compiler doesn't seem to find the definitions of several
> python related types (Py prefixed). There's probably some information
> that the compiler isn't getting, but I don't know what information to
> supply.

jythonc is the tool you need.  When you have a Jython file that you wish
to use as a Java class, just use jythonc on it.  i.e.- for module foo.py:

	jythonc foo.py

jythonc generates a .java file and also calls javac (unless told
otherwise) to compile it to foo.class and foo$_PyInner.class.  There's 2
catches to using jythonc: 1. You must inherit from a java class
(java.lang.Object if you have no special need for a java class) and 2. You
must provide a java method signature hint (@sig string) with a each
method.  Too see more about this, check out the jythonc docs at:

	http://jython.sourceforge.net/docs/jythonc.html

Look first at "Overriding/Implementing a java method" then at "Adding java
method signature to python methods docstrings" so you know what I'm
talking about, then you may want to look through the rest to see all the
gizmos it has.  If you run into trouble, post some code examples that you
are having trouble with and no doubt you'll get some useful replys.

> The option to turn on JIT doesn't seem to work on my machine, as the
> running time of python code doesn't seem to be affected by it (I am
> running the pystone.py from the test directory). jython executes pystone
> 4 times slower than cpython under jview (IE 5.0) will this improve with
> JIT.

I'm know very little about jview, but I've heard rumors that it is much
safer to use a javasoft VM.  I know- when people say things like this it
sounds like a gross overgeneralization and a bit scapegoat-ish, but if you
are new to Jython it's a good idea to eliminate needless complications.

Best of luck,
-Robert

[Jython-dev] Newbie on jython

[Syver E. <sy...@cy...>]

Hi!

I am contacting you to find what forums are the best to use when being a =
total newbie on jython and java. Should I use the comp.lang.python group =
or are there other forums that are more appopriate for jython questions.

I've been using cpython for about half a year and find it really =
excellent, I thought that jython would be a good entrance into the java =
world, and it seems to be.

I have a couple of questions that should be directed to the proper =
forum, but state them here anyway, if someone has the time too enlighten =
me.

There's a couple of things that I don't get yet. How can I compile a .py =
file into a java .class? I've read the documentation on this, but there =
seems to be something I am doing wrong. When trying to compile the .py =
file the javac compiler doesn't seem to find the definitions of several =
python related types (Py prefixed). There's probably some information =
that the compiler isn't getting, but I don't know what information to =
supply.

The option to turn on JIT doesn't seem to work on my machine, as the =
running time of python code doesn't seem to be affected by it (I am =
running the pystone.py from the test directory). jython executes pystone =
4 times slower than cpython under jview (IE 5.0) will this improve with =
JIT.

[Jython-dev] Applet & MS explorer problem..

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

SSdtIGJlZ2dpbmVyIGZvciBqeXRob24uLg0KDQpJIHdhbnQgdG8gcnVuIHNvbWUgYXBwbGV0IHVu
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Cmp5dGhvbiAyLjA=

[Jython-dev] The Use of Applet in jython

[<fo...@ha...>]

SGksIE15IG5hbWUgaXMgSHl1biBKb29uIEtpbS4NCkkgYW0gZnJvbSBLb3JlYS4NCkkgd2FudCB0
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Lg==

[Jython-dev] Problems with demo

[salvatore.didio <sal...@wa...>]

Hello,

I've just installed Jython on Win95
When I try to create the applets here is what I obtain:

C:\jython\Demo\applet>c:\jython\jythonc --core --deep --jar =
appletdemo.jar *.py
processing *
processing pawt.__init__

Required packages:
  java.awt
  java.applet

Creating adapters:
  java.awt.event.ActionListener used in *
  java.awt.event.WindowListener used in __init__

Creating .java files:
  * module
    ButtonDemo extends java.applet.Applet
Traceback (innermost last):
  File "C:\jython\Tools\jythonc\jythonc.py", line 5, in ?
  File "C:\jython\Tools\jythonc\main.py", line 300, in main
  File "C:\jython\Tools\jythonc\main.py", line 221, in doCompile
  File "C:\jython\Tools\jythonc\compile.py", line 381, in dump
  File "C:\jython\Tools\jythonc\compile.py", line 350, in processModule
  File "C:\jython\Tools\jythonc\PythonModule.py", line 434, in dump
  File "C:\jython\Tools\jythonc\jast\Output.py", line 17, in dump
IOError: File not found - .\jpywork\*.java

Thanks for your help

Re: [Jython-dev] applet problems

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

RE: [Jython-dev] applet problemsHi. Sorry for the too quick and not precise
remark:

jythonc applets compiled wrt the system classes of jdk 1.3  do not work under
IE and I think netscape 4.- either.

Reason: jdk 1.3 introduces new comp. hierarchy related events,
doing is job jythonc introduces explicit references to their handling procs in
the applet (proxy):

  ...
    public void processHierarchyBoundsEvent(java.awt.event.HierarchyEvent arg0)
{
        super.processHierarchyBoundsEvent(arg0);
    }

    public void processHierarchyEvent(java.awt.event.HierarchyEvent arg0) {
        super.processHierarchyEvent(arg0);
    }
 ...

java 1.1-like runtimes will fail to link the applet with their system classes
=> so the applet will not work.
Nothing to do directly with class-format or compiler issues.

In some sense this broad and sometime spurious references to the actual methods
of the base class break
some of the nice features of java related to robustness wrt to class changes.
But that's the way jythonc actually works.

regards, Samuele Pedroni.

PS: sorry for the too imprecise -> too technical move.