jython-users — Discussion of and questions about using Jython

R: [Jython-users] Import and NoClassDefFoundError

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

From: Edward Povazan <epo...@te...>
> I am using Jython 2.1 under XP Pro.
> 
> > import impi.core
> > dir(impi.core)
> ['__doc__', '__file__', '__name__', '__path__']
> 
> Hmm, this is strange, but I can acually:

That means that impi.core is a Python package,
you have a __init__.py both in impi and impi/core?

That's OK.

But so your from impi.core import * will never
get you the Java class. Anyway why the error?

The thing you haven't said to us
is that you are doing the 
    from impi.core import *
from a module inside impi.core, is that true?

Samuele.

Re: [Jython-users] Import and NoClassDefFoundError

[Edward P. <epo...@te...>]

> I'm not quite sure how you managed it, but I imagine at some point
> you had Impi in a file named impi.java? You may also not be using Jython
> 2.1?
That was my first thought ... I checked for rogue impi.java classes. Still
doesn't work. I did see similar questions in the archives, I think it is
something windows specific.

-Ed

RE: [Jython-users] Singleton [enforce by removing the constructor in the constructor itself]

[O'Brien-Strain, E. <eo...@ex...>]

If you want to enforce the singleton pattern you can remove the constructor
in the constructor itself.  That way only one object can be created.  For
example:

#Define the class
class Foo:
    def __init__(self,...):
        Foo.__init__ = None
        ...
    ...

#Create the one-and-only instance
Foo.instance = Foo(...)


All other code should use "Foo.instance" to refer to the singleton.  If any
other code erroneously tries to create a second Foo it will get a TypeError
complaining about trying to call a non-function.  (For a nicer error
message, instead of assigning __init__ to None you can assign it to a
function that raises a more meaningful exception.)   

__
Eamonn O'Brien-Strain
HP Labs
eo...@hp...




> -----Original Message-----
> From: Ype Kingma [mailto:yk...@xs...]
> Sent: Friday, March 22, 2002 3:27 PM
> To: jyt...@li...
> Subject: Re: [Jython-users] Singleton
> 
> 
> Stephen,
> 
> >Hi,
> >
> >I have read lots of stuff on creating the singleton design 
> pattern using
> >python and to be honest most of this information has left me 
> confused.
> >What is the best way to create the singleton in jython?
> 
> There is no single best way. You can use the borg pattern
> (use google to look for: python borg pattern singleton).
> Or you implement the singleton using module semantics:
> 
> class aSingle: pass
> 
> theSingle = aSingle()
> 
> and use itsModule.theSingle as the singleton.
> 
> Or you can implement it in java as a singleton,
> and access it from from jython.
> 
> There are probably at least a few more other ways.
> 
> >Thanks
> 
> Cheers,
> Ype
> 
> -- 
> 
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> https://lists.sourceforge.net/lists/listinfo/jython-users
> 

Re: [Jython-users] Import and NoClassDefFoundError

[Edward P. <epo...@te...>]

I am using Jython 2.1 under XP Pro.

> import impi.core
> dir(impi.core)
['__doc__', '__file__', '__name__', '__path__']

Hmm, this is strange, but I can acually:

import impi.core.Impi
dir(impi.core.Impi)

Which works as expected, showing all the static methods of the Impi class.
Impi is a class containing static methods only.

Do I have something set up wrong. My classpath is set to the root of my
project. Is there anything else?

Thanks
-Ed

Re: [Jython-users] Java obfuscator that works with jython generated jars?

[Stefan F. <st...@ti...>]

On Fri, 2002-03-22 at 15:57, Samuele Pedroni wrote:
> From: Stefan Farestam <st...@ti...>
> > 
> > I tried using retroguard to obfuscate a jar file
> > created by jythonc but got errors. 
> 
> What kind of errors, from the obfuscator
> or when running the obfuscated jar,
> or where the errors obfuscated too <wink>?

Nope, here they are (from retroguard.log):

# Logfile created on Fri Mar 22 16:02:06 PST 2002
#
# Jar file to be obfuscated:           rvscript.jar
# Target Jar file for obfuscated code: out.jar
# RetroGuard Script file used:         (none, defaults used)
#
# ERROR - corrupt class file: com/tibco/rvscript/StringIO.class

# Unrecoverable error during obfuscation:
# java.lang.NullPointerException
java.lang.NullPointerException
        at a.a.a.s.for(Unknown Source)
        at a.a.a.s.a(Unknown Source)
        at RetroGuard.a(Unknown Source)
        at RetroGuard.a(Unknown Source)
        at RetroGuard.main(Unknown Source)

> > I'm sonewhat
> > mystified as I thought that jythonc produced
> > standard Java bytecode.
> 
> More or less standard, although I have
> never used an obfuscator, I think
> that it can have a lot of trouble dealing
> with reflection and doing its job. 
> 
> regards.
> 
> > 
> > Has anyone been able to use retroguard or any other
> > obfuscator on jar produced by jythonc?
> 
> 
-- 
Stefan Farestam   Technical Alliance Mgr   Cell: +1 650 714 8350
st...@ti...  Strategic Alliances    Office: +1 650 846 8445
   www.tibco.com  TIBCO Software Inc.

Re: [Jython-users] Java obfuscator that works with jython generated jars?

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

From: Stefan Farestam <st...@ti...>
> 
> I tried using retroguard to obfuscate a jar file
> created by jythonc but got errors. 

What kind of errors, from the obfuscator
or when running the obfuscated jar,
or where the errors obfuscated too <wink>?

> I'm sonewhat
> mystified as I thought that jythonc produced
> standard Java bytecode.

More or less standard, although I have
never used an obfuscator, I think
that it can have a lot of trouble dealing
with reflection and doing its job. 

regards.

> 
> Has anyone been able to use retroguard or any other
> obfuscator on jar produced by jythonc?

Re: [Jython-users] Import and NoClassDefFoundError

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

> Hello All,
> 
> I've look in the archives, but only see questions, and no answers relating
> to this.
> I have a folder hierarchy impi/core/ and a .class file impi/core/Impi.class
> 
> when I 'from impi.core import *' from another module, I get
> 'java.lang.NoClassDefFoundError: java.lang.NoClassDefFoundError:
> impi/core/impi (wrong name: impi/core/Impi)'
> 
> Is there a quick fix for this?
> 

Under which OS?
What does:

import impi.core
dir(impi.core)

display? Impli or impli

Samuele.
 

Re: [Jython-users] Import and NoClassDefFoundError

[Kevin B. <kb...@ca...>]

Hmm.

I'm not quite sure how you managed it, but I imagine at some point
you had Impi in a file named impi.java? You may also not be using Jython 
2.1?

Windows' case-insensitive filesystem is unfriendly to Java's 
case-sensitive class names & one-class-one-file philosophy.

I'd suggest doing a clean build of all your Java code related to Impi. 
This will probably identify some class that is using 'impi' instead of 
'Impi'.  'grep' may also do it.

kb

Edward Povazan wrote:

>Hello All,
>
>I've look in the archives, but only see questions, and no answers relating
>to this.
>I have a folder hierarchy impi/core/ and a .class file impi/core/Impi.class
>
>when I 'from impi.core import *' from another module, I get
>'java.lang.NoClassDefFoundError: java.lang.NoClassDefFoundError:
>impi/core/impi (wrong name: impi/core/Impi)'
>
>Is there a quick fix for this?
>
>Thanks
>-Ed
>
>
>_______________________________________________
>Jython-users mailing list
>Jyt...@li...
>https://lists.sourceforge.net/lists/listinfo/jython-users
>

Re: [Jython-users] IPC

[Kevin B. <kb...@ca...>]

One more I forgot to mention, which may be suitable for your application:

If you are going to have one of your processes spawn the other, you can 
just use os.popen* (in CPython) or Java's Runtime.exec (in Jython until 
I or someone else implements popen* functions) to spawn the child 
process. The parent then reads from/writes to the returned file handles, 
and the child reads/writes stdin/stdout.

kb

Kevin Butler wrote:

> You have several options, ranging in rough order of difficulty:
>
> - Python-specific RPC technology (PYRO http://pyro.sourceforge.net/ or 
> DOPY http://www.users.cloud9.net/~proteus/dopy/)
>    I actually haven't used either, as I've needed cross language 
> interoperability, but I probably would use one of them if I were doing 
> all-Python RPC
>
> - Python-based CORBA solution (Fnorb or omniorb and possibly Java's 
> CORBA interfaces)
>
> - XML-based RPC technology (xmlrpc/soap) (haven't done much with these)
>
> - custom sockets (probably using pickles, maybe SimpleTCPServer or 
> BaseHTTPServer)
>
> - some other communication mechanism you dream up - write to a file, 
> database, etc.
>
> In spite of what RPC vendors would have you think, none of this is 
> very difficult, and unless you
> have significant stability or performance requirements, all should be 
> quite suitable.  I imagine that
> if PYRO or DOPY works for you, they will be significantly easier than 
> any of the others, but all
> the others are pretty similar in difficulty.
>
> IMO, YMMV, etc.
>
> kb
>
> Stephen Naicken wrote:
>
>> I have a system made up of two parts.  One in Jython and the other in
>> CPython.  The reason for this is that I could not find a Gnutella
>> library in CPython, but I could in Java.  Also I have been having
>> difficulties with BerkeleyDB Java bindings, so I decided to use 
>> CPython's bsddb.
>>
>> Anyway, I would like the jython and python processes to communicate with
>> each other.  I was think of IPC using scokets, but I'm not sure if this
>> is the best option.
>>
>> I'd be grateful for any advice on this as I have not done this sort of
>> thing before.  Alternatively if anyone knows of a good python gnutella
>> library (like Jtella), that would be an alternative solution.
>>
>> Thanks Again.
>>
>> Stephen
>>
>>
>> _______________________________________________
>> Jython-users mailing list
>> Jyt...@li...
>> https://lists.sourceforge.net/lists/listinfo/jython-users
>>
>
>
>
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> https://lists.sourceforge.net/lists/listinfo/jython-users

[Jython-users] Java obfuscator that works with jython generated jars?

[Stefan F. <st...@ti...>]

I tried using retroguard to obfuscate a jar file
created by jythonc but got errors. I'm sonewhat
mystified as I thought that jythonc produced
standard Java bytecode.

Has anyone been able to use retroguard or any other
obfuscator on jar produced by jythonc?

Thanks,
Stefan

Re: [Jython-users] Singleton

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

Stephen,

>Hi,
>
>I have read lots of stuff on creating the singleton design pattern using
>python and to be honest most of this information has left me confused.
>What is the best way to create the singleton in jython?

There is no single best way. You can use the borg pattern
(use google to look for: python borg pattern singleton).
Or you implement the singleton using module semantics:

class aSingle: pass

theSingle = aSingle()

and use itsModule.theSingle as the singleton.

Or you can implement it in java as a singleton,
and access it from from jython.

There are probably at least a few more other ways.

>Thanks

Cheers,
Ype

-- 

Re: [Jython-users] IPC

[Kevin B. <kb...@ca...>]

You have several options, ranging in rough order of difficulty:

- Python-specific RPC technology (PYRO http://pyro.sourceforge.net/ or 
DOPY http://www.users.cloud9.net/~proteus/dopy/)
    I actually haven't used either, as I've needed cross language 
interoperability, but I probably would use one of them if I were doing 
all-Python RPC

- Python-based CORBA solution (Fnorb or omniorb and possibly Java's 
CORBA interfaces)

- XML-based RPC technology (xmlrpc/soap) (haven't done much with these)

- custom sockets (probably using pickles, maybe SimpleTCPServer or 
BaseHTTPServer)

- some other communication mechanism you dream up - write to a file, 
database, etc.

In spite of what RPC vendors would have you think, none of this is very 
difficult, and unless you
have significant stability or performance requirements, all should be 
quite suitable.  I imagine that
if PYRO or DOPY works for you, they will be significantly easier than 
any of the others, but all
the others are pretty similar in difficulty.

IMO, YMMV, etc.

kb

Stephen Naicken wrote:

>I have a system made up of two parts.  One in Jython and the other in
>CPython.  The reason for this is that I could not find a Gnutella
>library in CPython, but I could in Java.  Also I have been having
>difficulties with BerkeleyDB Java bindings, so I decided to use 
>CPython's bsddb.
>
>Anyway, I would like the jython and python processes to communicate with
>each other.  I was think of IPC using scokets, but I'm not sure if this
>is the best option.
>
>I'd be grateful for any advice on this as I have not done this sort of
>thing before.  Alternatively if anyone knows of a good python gnutella
>library (like Jtella), that would be an alternative solution.
>
>Thanks Again.
>
>Stephen
>
>
>_______________________________________________
>Jython-users mailing list
>Jyt...@li...
>https://lists.sourceforge.net/lists/listinfo/jython-users
>

[Jython-users] Import and NoClassDefFoundError

[Edward P. <epo...@te...>]

Hello All,

I've look in the archives, but only see questions, and no answers relating
to this.
I have a folder hierarchy impi/core/ and a .class file impi/core/Impi.class

when I 'from impi.core import *' from another module, I get
'java.lang.NoClassDefFoundError: java.lang.NoClassDefFoundError:
impi/core/impi (wrong name: impi/core/Impi)'

Is there a quick fix for this?

Thanks
-Ed

Re: [Jython-users] Swing examples

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

Ashish,


The default list cell renderer renders the objects in the list
with the result of toString.  Instances of Python classes do
not return the result of __repr__ or __str__ for the Java
toString method.  You could write a replacement cell renderer
that calls the __str__ method for PyInstances.

Perhaps something like in Jython:

class PyInstanceListCellRenderer(DefaultListCellRenderer):
   def getListCellRendererComponent(self,list, \
           value, index, selected, focus):
     return DefaultListCellRenderer.getListCellRendererComponent(self,\
           list,`value`,index,selected,focus)


myList = JList(cellRenderer=PyInstanceListCellRenderer())


Jeff Emanuel



BillWorker 2i wrote:

> Okay, I just have modified your code to include a few more classes. If you
> run the script you will see that only for PyClass5, the one that inherits
> from java.lang.Object, the JList shows a proper string in the list.
> 
> Ashish
> 
> ----------  code ---------
> import java
> import javax.swing as swing
> 
> class PyClass1:
> pass
> 
> class PyClass2:
> def __repr__(self):
> return 'PyClass2'
> 
> class PyClass3:
> def __str__(self):
> return 'PyClass3'
> 
> class PyClass4:
> def toString(self):
> return 'PyClass4'
> 
> class PyClass5(java.lang.Object):
> def toString(self):
> return 'PyClass5'
> 
> 
> class TestModel(swing.AbstractListModel):
> def __init__(self):
> self.classList = [PyClass1(), PyClass2(), PyClass3(), PyClass4(),
> PyClass5()]
> 
> def getElementAt(self, i):
> return self.classList[i]
> 
> def getSize(self):
> return len(self.classList)
> 
> 
> frame = swing.JFrame('test')
> jlist = swing.JList(TestModel())
> frame.contentPane.add(jlist)
> frame.pack()
> frame.visible = 1
> 
> 
> 
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> https://lists.sourceforge.net/lists/listinfo/jython-users
> 

Re: [Jython-users] IPC

[Michel P. <mi...@di...>]

> I'd be grateful for any advice on this as I have not done this sort
of
> thing before.  Alternatively if anyone knows of a good python
gnutella
> library (like Jtella), that would be an alternative solution.

I have a CPython system (Zope) talking to a Jython system via xml-rpc.
 
xmlrpcserver.py can be found at:

http://www.pythonware.com/products/xmlrpc/index.htm

it works fine in jython.  Note, xml-rpc will only give you simple data

pasing, numbers, strings, lists, "structs" etc.

-Michel

[Jython-users] IPC

[Stephen N. <ste...@co...>]

I have a system made up of two parts.  One in Jython and the other in
CPython.  The reason for this is that I could not find a Gnutella
library in CPython, but I could in Java.  Also I have been having
difficulties with BerkeleyDB Java bindings, so I decided to use 
CPython's bsddb.

Anyway, I would like the jython and python processes to communicate with
each other.  I was think of IPC using scokets, but I'm not sure if this
is the best option.

I'd be grateful for any advice on this as I have not done this sort of
thing before.  Alternatively if anyone knows of a good python gnutella
library (like Jtella), that would be an alternative solution.

Thanks Again.

Stephen

Re: [Jython-users] Printing without a newline

[Michel P. <mi...@di...>]

-------------------
> 
> Thanks, Kevin ! I knew it must be something simple, but I definitely
> couldn't find it after a quick look of the python  documentation.
> 
> As a matter of fact, I looked at the documentation python.org and I 
didn't
> find any mention of the things that you mention. Could you please
give 
me a
> hint, where stuff like that can be looked up ? (I guess, other than
the
> source)

The Python language reference:

http://www.python.org/doc/current/ref/print.html

-Michel

[Jython-users] Possibly FAQ re Junit

[Dave D. <d.j...@hu...>]

Dear All,
I have searched the archives and posted on the Junit list.
No definitive answer, so trying again. ;)
I have been using unittest with Jython but would like to use JUnit
for teaching/illustrative purposes. The maillings suggest that use
of JUnit and automatic suite generation is problematical due to reflection.
I have tried using docstrings and jythonc but without much success.
Does there exist a port of the JUnit distribution demo ( Money ) in
jython that successfully works with GUI runner that I can use as a
leg-up ?
	Many thanks
	David

________________________________________________________________________________

  	         ********************************************************
                 *     David Dench                          		*
                 *     School of Computing & Mathematics    		*
                 *     The University of Huddersfield       		*
                 *     Tel:  01484  472083	     			*
                 *     email: d.j...@hu...   	 		*
    		 *     web:   http://scom.hud.ac.uk/scomdjd     	*
                 ********************************************************
________________________________________________________________________________

Re: [Jython-users] Singleton

[Jan W. <j.w...@sc...>]

On Thu, Mar 21, 2002 at 11:02:06PM +0000, Stephen Naicken wrote:
> Hi,
ReHi,
> I have read lots of stuff on creating the singleton design pattern usin=
g
> python and to be honest most of this information has left me confused.
> What is the best way to create the singleton in jython?

Well, in http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66531 Al=
ex
Martelli argues that you don't want a singleton in most cases. He propose=
s a
different pattern he calls Borg.
The implementation works just as well in Jython.

Cheerio,
--=20
J.W...@sc...  -  Fon +4970719457-257 Fax-211
science+computing ag - Hagellocher Weg 71-75 - 72070 T=FCbingen
In case you're not a computer person, I should probably point out that "R=
eal
Soon Now" is a technical term meaning "sometime before the heat-death of =
the
universe, maybe". (Scott Fahlman)

Re: [Jython-users] Executable inclusions in strings?

[BillWorker 2. <bil...@in...>]

Hey Brad,

Are you porting the jwaa to jython??

Ashish

[Jython-users] Singleton

[Stephen N. <ste...@co...>]

Hi,

I have read lots of stuff on creating the singleton design pattern using
python and to be honest most of this information has left me confused.
What is the best way to create the singleton in jython?

Thanks

Stephen

RE: [Jython-users] Executable inclusions in strings?

[O'Brien-Strain, E. <eo...@ex...>]

Another idiom is to use one of the dictionaries that the language provides
such as "globals()" or the "__dict__" attribute of an object.  For example:


title = "My title"
body  = "Blah, blah"
print """
<html>
	<head>
		<title>%(title)s</title>
	</head>
	<body>%(body)s</body>
</html>""" % globals()


__
Eamonn O'Brien-Strain
HP Labs
eo...@hp...

========================================================

> From: Ype Kingma [mailto:yk...@xs...]
[...]
> my = {}
> my['title'] = "My title"
> my['body'] = "Blah, blah"
> print """
> <html>
> 	<head>
> 		<title>%(title)s</title>
> 	</head>
> 	<body>%(body)s</body>
> </html>""" % my

==========================================================

> From: Brad Cox [mailto:bc...@vi...]
[...] 
> Does python have a way of interpolating variables into strings, along 
> the lines of this perl example?
> 
> my $title = "My title";
> my $body = "Blah, blah";
> print """
> <html>
> 	<head>
> 		<title>$title</title>
> 	</head>
> 	<body>$body</body>
> </html>"""

Re: [Jython-users] Executable inclusions in strings?

[Brad C. <bc...@vi...>]

Thanks! I was afraid I'd have to import my java multi-line string 
preprocessor from java to do this in python. See 
http://virtualschool.edu/jwaa under Mls.

At 8:39 PM +0100 3/21/02, Ype Kingma wrote:
>Brad,
>
>>Does python have a way of interpolating variables into strings, 
>>along the lines of this perl example?
>>
>  >my $title = "My title";
>>my $body = "Blah, blah";
>>print """
>><html>
>>	<head>
>>		<title>$title</title>
>>	</head>
>>	<body>$body</body>
>></html>"""
>
>my = {}
>my['title'] = "My title"
>my['body'] = "Blah, blah"
>print """
><html>
>	<head>
>		<title>%(title)s</title>
>	</head>
>	<body>%(body)s</body>
></html>""" % my
>
>See http://www.python.org/doc/current/lib/typesseq-strings.html
>
>Regards,
>Ype
>
>
>--
>
>_______________________________________________
>Jython-users mailing list
>Jyt...@li...
>https://lists.sourceforge.net/lists/listinfo/jython-users


-- 
Brad Cox, PhD; bc...@vi... 703 361 4751
o For industrial age goods there were checks and credit cards.
    For everything else there is http://virtualschool.edu/mybank
o Java Interactive Learning Environment http://virtualschool.edu/jile
o Java Web Application Architecture: http://virtualschool.edu/jwaa

Re: [Jython-users] Executable inclusions in strings?

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

Brad,

>Does python have a way of interpolating variables into strings, along the lines of this perl example?
>
>my $title = "My title";
>my $body = "Blah, blah";
>print """
><html>
>	<head>
>		<title>$title</title>
>	</head>
>	<body>$body</body>
></html>"""

my = {}
my['title'] = "My title"
my['body'] = "Blah, blah"
print """
<html>
	<head>
		<title>%(title)s</title>
	</head>
	<body>%(body)s</body>
</html>""" % my

See http://www.python.org/doc/current/lib/typesseq-strings.html

Regards,
Ype


-- 

[Jython-users] Executable inclusions in strings?

[Brad C. <bc...@vi...>]

Does python have a way of interpolating variables into strings, along 
the lines of this perl example?

my $title = "My title";
my $body = "Blah, blah";
print """
<html>
	<head>
		<title>$title</title>
	</head>
	<body>$body</body>
</html>"""
-- 
Brad Cox, PhD; bc...@vi... 703 361 4751
o For industrial age goods there were checks and credit cards.
    For everything else there is http://virtualschool.edu/mybank
o Java Interactive Learning Environment http://virtualschool.edu/jile
o Java Web Application Architecture: http://virtualschool.edu/jwaa