jython-users — Discussion of and questions about using Jython

[Jython-users] Install Q..

[cindy <inf...@pi...>]

Hi,
I'm a little confude as to how to install jython. I pulled down the
tar-ball and untared it. Do I need to use ListOff to install it?
From what I read of ListOff, it sounded like I use this product to
bundle my classes. I'm using Blackdown distro of java 1.3.0.
My current release of python is 1.5.2. The CLASSPATH is
set to '/usr/local/jdk1.3/j2sdk1.3.0/bin. I installed jython
in /usr/local/jython-20010320. I went to the demo directory to
execute some of the modules and had no luck. To execute the
demo module simple.py do I enter 'jython simple.py' or
'java simple.py?
TIA.
Wayne

Re: [Jython-users] Jython/Java and Reflection

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

[mike]

>I am running into a problem trying to subclass a java class from
>Jython2.0. The problem lies in the fact that the java class I extend from
>uses reflection to implement the template method pattern. The methods it is
>looking for is implemented in my jython class. Here is an example using the 
>JUnit framework which illustrates my problem:
>
>---- example.py ----
>import java
>import junit
>
>class MyJavaClassTest(junit.framework.TestCase):
>
>	def __init__(self, name):
>		junit.framework.TestCase.__init__(self, name)
>
>	def setUp(self):
>		"@sig public void setUp()"
>		pass
>
>	def testMyJavaClass(self):
>		"@sig public void testMyJavaClass()"
>		pass
>
>junit.textui.TestRunner.run(MyJavaClassTest("testMyJavaClass"))
>---- end example.py ----
>
>Running this from the command line I get:
>
>$ cmd /c c:/devel/jython-2.1/jython.bat example.py
>.F
>Time: 0
>There was 1 failure:
>1) testMyJavaClass(org.python.proxies.__main__$MyJavaClassTest$1) "Method "testM
>yJavaClass" not found"
>
>FAILURES!!!
>Tests run: 1,  Failures: 1,  Errors: 0
>
>As you can see the JUnit TestCase class is using reflection to look for the
>testMyJavaClass method. Will this example only work if I run jythonc?

Yes.

>It
>looks like the autogenerated proxy class is ignoring the "@sig"
>information.

Correct. This is unlikely to change.

>Also, with the upcoming 2.1 release, will function attributes be used to 
>replace the "@sig" syntax?

No.

You will have to override the runTest() method in order to subclass
TestCase:

import java, junit
class MyJavaClassTest(junit.framework.TestCase):
	def __init__(self, name):
		junit.framework.TestCase.__init__(self, name)
	def setUp(self):
		pass
	def runTest(self):
		self.testMyJavaClass()
	def testMyJavaClass(self):
		print "testing"

junit.textui.TestRunner.run(MyJavaClassTest("someName"))

regards,
finn

Re: [Jython-users] using jython as glue

[Jim A. <ji...@tr...>]

Mark Ackerman wrote:
> 
> I'm just starting to use jython as a glue language in a java program
> (middleware research), and I'm a bit lost.  I can successfully call any
> method in a standard java class (eg, java.io), but I can't figure out how to
> call my own classes and methods.  What's the magic I need?
> 
>                 Mark

This works for me:

First import your classes:

  from dsi.fs import FillFiller, Segment

Then call a static method:

  cmdResult = FillFiller.FillSegments( ... )  # Finds the matching
static method

or just use a class defined in Java:

 s = Segment( ... )   # This calls the Java constructor with matching
parameters.

It's really toooo easy ! What problems are you having ?

-- 
                                 __o
Jim Adrig                      _ \<,_
ji...@tr...          ' `/ ' `
                  ___________ `-'  `-'

[Jython-users] using jython as glue

[Mark A. <ack...@go...>]

I'm just starting to use jython as a glue language in a java program
(middleware research), and I'm a bit lost.  I can successfully call any
method in a standard java class (eg, java.io), but I can't figure out how to
call my own classes and methods.  What's the magic I need?

                Mark
                              

[Jython-users] Jython/Java and Reflection

[<mi...@hi...>]

I am running into a problem trying to subclass a java class from
Jython2.0. The problem lies in the fact that the java class I extend from
uses reflection to implement the template method pattern. The methods it is
looking for is implemented in my jython class. Here is an example using the 
JUnit framework which illustrates my problem:

---- example.py ----
import java
import junit

class MyJavaClassTest(junit.framework.TestCase):

	def __init__(self, name):
		junit.framework.TestCase.__init__(self, name)

	def setUp(self):
		"@sig public void setUp()"
		pass

	def testMyJavaClass(self):
		"@sig public void testMyJavaClass()"
		pass

junit.textui.TestRunner.run(MyJavaClassTest("testMyJavaClass"))
---- end example.py ----

Running this from the command line I get:

$ cmd /c c:/devel/jython-2.1/jython.bat example.py
.F
Time: 0
There was 1 failure:
1) testMyJavaClass(org.python.proxies.__main__$MyJavaClassTest$1) "Method "testM
yJavaClass" not found"

FAILURES!!!
Tests run: 1,  Failures: 1,  Errors: 0

As you can see the JUnit TestCase class is using reflection to look for the
testMyJavaClass method. Will this example only work if I run jythonc? It
looks like the autogenerated proxy class is ignoring the "@sig"
information.

Also, with the upcoming 2.1 release, will function attributes be used to 
replace the "@sig" syntax?

--mike

Re: [Jython-users] Storing code objects

[Jim A. <ji...@tr...>]

Finn Bock wrote:

> The code in a PyTableCode is implemented by a
> dynamicly created java class and we do not keep the original java
> bytecode around. Even if we kept and saved the java bytecode, loading a
> page would still have to recreate a java class for each PyCode.

Thanks, now I see why that approach was so slow...

> It pains me a lot to say it, but this is one situation where jython's
> compile-to-bytecode approach fails to deliver high performance.
> 
> Depending on the design of your forms, if you could collect all the
> expressions found on a page into one jython source string:
> 
> """
> def func001():
>    return Customer.Name
> def func002():
>    for p in Customer.Phones:
>       print p
> """
> 
> then the slow class creation would only occur once for the page.
> 
>   PyCode code = __builtin__.compile(pagesrc, "<string>", "exec");
>   PyStringMap dict = new PyStringMap()
>   Py.exec(code, dict, dict)
> 
> and the evaluation of each expression would run at full jython speed:
> 
>   PyObject result = dict.__getitem__("func001").__call__();

This is very interesting, I had not considered that approach, since I
did not clearly understand where the slowdown was (creating classes). I
probably could have had something running by now had I thought of it...

But in the meantime, I have been working on a different (more work!)
approach where I build jython source for the entire page, with
'callbacks' to Java routines that do extra work:

  pagePCL = ""
  errorList = []
  ...
  cmdResult = Customer.Total     // User's original expression
  cmdResult = FillFiller.FormatResults(cmdResult,'#,##0.00')
  cmdResult = FillFiller.FillSegments(cmdResult,
((525,2322,478)),false,10,'',error)
  errorList.append(error)
  pagePCL += cmdResult
  ...

This approach requires more restructuring of my code so I have not been
able to benchmark it yet: I'm still working on all the 'callbacks'. Some
of them could be rewritten in Python too but I'm not sure that would buy
me anything.

Then I was going to build a 'cache' (HashMap) of the code-objects for
the forms in a servlet so I can just keep the compiled pages in memory
(I got this idea while checking out 'Python Server Pages':
http://www.ciobriefings.com/psp/ ). There will be hundreds, and
eventually maybe thousands, of forms being run so I'm hoping this will
be OK: a JDOM tree is cached along with an array of pages (although I
may be able to get rid of that with more custom structures later...).

Later, with some more restructuring/rewriting I might be able to build
complete Python forms and compile them to Java classes (and dynamically
load them?), this would save the initial compile (but not much more?).

Thanks again for your reply; do you see any problems with my new
approach ?

-- 
                                 __o
Jim Adrig                      _ \<,_
ji...@tr...          ' `/ ' `
                  ___________ `-'  `-'

[Jython-users] Jython on leJos?

[Stephen R. F. <fi...@mo...>]

Do you think a program in Jython would be able to run on leJos, the
JavaVM for Lego Mindstorms robots?

  http://lejos.sourceforge.net/

If I had Mindstorms I would give it a try.  Has anyone out there tried
this?  How about running Jython programs on the KVM? J2ME? Any, Jython
on small platform stories out there?

Stephen

Re: [Jython-users] Storing code objects

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

On Mon, 19 Mar 2001 10:40:40 -0800, you wrote:

>Question:
>
>How do I comvert a compiled code object to some kind of bytestream?
>'Pickle' can't handle PyCode ("can't pickle ...PyTableCode object"), and
>PyCode is not serializable. Am I missing something or is there no way to
>do this easily?

There is no way. Sorry. The code in a PyTableCode is implemented by a
dynamicly created java class and we do not keep the original java
bytecode around. Even if we kept and saved the java bytecode, loading a
page would still have to recreate a java class for each PyCode.

>Backround:
>
>I am prototyping a program that uses Jython to allow users to design
>forms by entering Jython expressions which are evaluated based on a
>large set of XML data that is 'scoped' into the PythonInterpreter
>beforehand. (Example: 'Customer.Name' or 'for p in Customer.Phones:
>print p') We have built a GUI that displays the forms and allows entry
>of the expressions, the 'definition' of the form is stored in XML along
>with Fonts, justification, and other formatting info. After each
>expression is evaluated the result is 'massaged' using various Java
>routines to build a complete page.
>
>The previous version used JavaScript (Rhino) but I'm trying to switch it
>to Python to make it easier for the form designers.
>
>I'm having a problem, though, with the speed: when interpreting
>expressions Jython is half the speed of Rhino: this is critical for this
>app.
>
>I timed the compile compared the the 'eval' and found the compile takes
>90% of the time:
>
> PyCode code = __builtin__.compile(evalLine, "<string>", "eval");  //
>90%
>
> PyObject result = python.eval( (PyCode)code );                    //
>10% !!
>
>If I could store the compiled 'code objects' within the forms somehow I
>think I could increase the speed of the forms 10x, but I can't figure
>out a way to get some kind of 'bytestream' of the code object.

It pains me a lot to say it, but this is one situation where jython's
compile-to-bytecode approach fails to deliver high performance.

Depending on the design of your forms, if you could collect all the
expressions found on a page into one jython source string:

"""
def func001():
   return Customer.Name
def func002():
   for p in Customer.Phones:
      print p
"""

then the slow class creation would only occur once for the page. 

  PyCode code = __builtin__.compile(pagesrc, "<string>", "exec");
  PyStringMap dict = new PyStringMap()
  Py.exec(code, dict, dict)

and the evaluation of each expression would run at full jython speed:

  PyObject result = dict.__getitem__("func001").__call__();


I hope this helps a little.

regards,
finn

RE: [Jython-users] How to call external commands

[John E. C. <jc...@ve...>]

Brian,

I simply forgot about the exec method.  And as the article you referred to
points out - it is an easy API to misuse. =20

thanks for the excellent advice, example and article,=20

John

 At 05:06 PM 3/19/01 -0600, Brian Zimmer wrote:=20
>
> Here's an interesting article pertaining to Runtime/Process:
> =A0
>
> <http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html>http://w
> ww.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html
> =A0
> brian
>>
>> -----Original Message-----=20
>> From: jyt...@li...
>> [mailto:jyt...@li...]On Behalf Of Brian=
 Zimmer=20
>> Sent: Monday, March 19, 2001 4:42 PM=20
>> To: John E. Conlon; jyt...@li...=20
>> Subject: RE: [Jython-users] How to call external commands
>>
>> Here's an extremely simple example (by no means production, but could get
>> you on your way):=20
>>
>> """ =20
>> =A0Process the command. =20
>> """=20
>>
>> from java.lang import Runtime =20
>> from java.io import BufferedInputStream=20
>>
>> p =3D Runtime.getRuntime().exec("ls") =20
>> #p.waitFor() =20
>> stream =3D BufferedInputStream(p.getInputStream())=20
>>
>> e =3D []=20
>>
>> r =3D stream.read() =20
>> while r !=3D -1: =20
>> =A0e.append(r) =20
>> =A0r =3D stream.read()=20
>>
>> print "".join(map(chr, e))=20
>>
>> Running it produces:=20
>>
>> D:\home\development\python>jython process.py =20
>> HTTPSession$py.class =20
>> HTTPSession.py =20
>> __init__.py =20
>> a5.py =20
>> aar.py =20
>> acl.py =20
>> aioobe.py =20
>> ant.py =20
>> atl.py =20
>> caps.py =20
>> cont.py=20
>>
>> brian=20
>>
>> -----Original Message----- =20
>> From: jyt...@li... =20
>>
>> [<mailto:jyt...@li...>mailto:jython-users-adm
>> in...@li...]On Behalf Of John E. =20
>> Conlon =20
>> Sent: Monday, March 19, 2001 4:22 PM =20
>> To: jyt...@li... =20
>> Subject: [Jython-users] How to call external commands=20
>>
>> Hi Jython users,=20
>>
>> I would like to replace my bat and sh startup scripts with jython py =20
>> scripts.=A0 But after experimentation I can not figure out how to call =
=20
>> external executables in my underlying system.=A0 =20
>> Have seen comments that the os.system(name) command is not yet
implemented. =20
>> =A0Is there any other way to launch external programs without the=
 os.system =20
>> command?=20
>>
>> thanks for any suggestions,=20
>>
>> John=20
>>
>> _______________________________________________ =20
>> Jython-users mailing list =20
>> Jyt...@li... =20
>>
>> <http://lists.sourceforge.net/lists/listinfo/jython-users>http://lists.so
>> urceforge.net/lists/listinfo/jython-users=20
>

************************************************************************
John E. Conlon
jc...@ve...
tel: (770) 886-5470
fax: (770) 888-6894
<http://www.verticon.com/>www.verticon.com
************************************************************************

Re: [Jython-users] Jython GUI debugger/IDE

[D-Man <ds...@ri...>]

On Mon, Mar 19, 2001 at 10:03:17PM +0200, Kexx wrote:
| 
|    I've given up trying to make Idle (from Python) work with Jython (no
|    TkInter module).
|    
|    I can edit the files using it, of course, but I would like to debug in
|    GUI mode, and do the rest of the wonderful things the IDE supports.
|    
|    Any alternatives I should consider?
|    
|    I use JDK 1.3 on Win2k, without "X Window System", so DDD frontends
|    won't work, I guess...

XFree86 is supposed to work on windows.  I didn't try very hard, but I
did get the background to appear.  If you can get XFree working then
you can use DDD.  

You could also try Vide (www.objectcentral.com/vide.htm) or
NetBeans (www.netbeans.org).  They are Java debuggers (ides) and can
therefore debug the java the interpreter is implemented in, but
probably won't be able to handle the python source very well.

I have used NetBeans only a little, and it seems rather nice.  I
haven't tried Vide yet.  When I was using a Unix system I thought that
DDD was really good, except I don't really like it's choice of
toolkits.  Alternatively, print works on all systems ;-).

|    P.S. I would appreciate replys to [1]ke...@in... if at all possible
|    (sourceforge mailinglists confuse me).

You simply subscribe to the mailing list.  Then whenever someone (like
me replying to your message) sends a message to the list's address,
you get a copy sent to you.

Are you subscribed to the list?


-D

RE: [Jython-users] How to call external commands

[Joseph S. B. I. <jo...@ba...>]

Brian Zimmer a =E9crit:
> Here's an extremely simple example (by no means production, but could=

> get you on your way):

Here's what I've been using.
For outwriter and errwriter, one can pass either PrintStreams,
OutputStreamWriters, or (if you don't care about the output) None.


execvbuf =3D zeros(8192, "c")

def execv(name, outwriter, errwriter):

    # I don't know why we need to check for PrintStream,
    # given that instanceof(PrintStream, OutputStream)...
    # or maybe I need a mix of isinstance() and issubclass()...
    #
    if isinstance(outwriter, OutputStream) or isinstance(outwriter, Pri=
ntStream):
        outwriter =3D OutputStreamWriter(outwriter)
    if isinstance(errwriter, OutputStream) or isinstance(errwriter, Pri=
ntStream):
        errwriter =3D OutputStreamWriter(errwriter)

    process =3D getRuntime().exec(name)
    stdout =3D InputStreamReader(process.getInputStream())
    stderr =3D InputStreamReader(process.getErrorStream())

    while 1:
        if stdout <> None:
            if stdout.ready():
                n =3D stdout.read(execvbuf)
                if n =3D=3D -1:
                    stdout =3D None
                    print "stdout now None"
                    continue
                if outwriter <> None:
                    outwriter.write(execvbuf, 0, n)
                    continue
        if stderr <> None:
            if stderr.ready():
                n =3D stderr.read(execvbuf)
                if n =3D=3D -1:
                    stderr =3D None
                    print "stderr now None"
                    continue
                if errwriter <> None:
                    errwriter.write(execvbuf, 0, n)
                    continue
        try:
            status =3D process.exitValue()
            if status <> 0:
                print "%s returned status %d" % (name, status)
            return status
        except:
            sleep(200)

Re: [Jython-users] How to call external commands

[D-Man <ds...@ri...>]

On Mon, Mar 19, 2001 at 05:21:58PM -0500, John E. Conlon wrote:
| Hi Jython users,
| 
| I would like to replace my bat and sh startup scripts with jython py
| scripts.  But after experimentation I can not figure out how to call
| external executables in my underlying system.  

Why not use CPython for this?  Do need access to java classes in these
startup scripts?

-D

RE: [Jython-users] How to call external commands

[Brian Z. <bz...@ig...>]

Here's an interesting article pertaining to Runtime/Process:
=20
http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html
<http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html>=20
=20
brian

-----Original Message-----
From: jyt...@li...
[mailto:jyt...@li...]On Behalf Of Brian
Zimmer
Sent: Monday, March 19, 2001 4:42 PM
To: John E. Conlon; jyt...@li...
Subject: RE: [Jython-users] How to call external commands



Here's an extremely simple example (by no means production, but could
get you on your way):=20

"""=20
 Process the command.=20
"""=20

from java.lang import Runtime=20
from java.io import BufferedInputStream=20

p =3D Runtime.getRuntime().exec("ls")=20
#p.waitFor()=20
stream =3D BufferedInputStream(p.getInputStream())=20

e =3D []=20

r =3D stream.read()=20
while r !=3D -1:=20
 e.append(r)=20
 r =3D stream.read()=20

print "".join(map(chr, e))=20

Running it produces:=20

D:\home\development\python>jython process.py=20
HTTPSession$py.class=20
HTTPSession.py=20
__init__.py=20
a5.py=20
aar.py=20
acl.py=20
aioobe.py=20
ant.py=20
atl.py=20
caps.py=20
cont.py=20

brian=20


-----Original Message-----=20
From: jyt...@li...=20
[ mailto:jyt...@li...
<mailto:jyt...@li...> ]On Behalf Of John E.=20
Conlon=20
Sent: Monday, March 19, 2001 4:22 PM=20
To: jyt...@li...=20
Subject: [Jython-users] How to call external commands=20


Hi Jython users,=20

I would like to replace my bat and sh startup scripts with jython py=20
scripts.  But after experimentation I can not figure out how to call=20
external executables in my underlying system. =20

Have seen comments that the os.system(name) command is not yet
implemented.=20
 Is there any other way to launch external programs without the
os.system=20
command?=20

thanks for any suggestions,=20

John=20

_______________________________________________=20
Jython-users mailing list=20
Jyt...@li...=20
http://lists.sourceforge.net/lists/listinfo/jython-users
<http://lists.sourceforge.net/lists/listinfo/jython-users> =20

RE: [Jython-users] How to call external commands

[Brian Z. <bz...@ig...>]

Here's an extremely simple example (by no means production, but could
get you on your way):

"""
 Process the command.
"""

from java.lang import Runtime
from java.io import BufferedInputStream

p =3D Runtime.getRuntime().exec("ls")
#p.waitFor()
stream =3D BufferedInputStream(p.getInputStream())

e =3D []

r =3D stream.read()
while r !=3D -1:
 e.append(r)
 r =3D stream.read()

print "".join(map(chr, e))

Running it produces:

D:\home\development\python>jython process.py
HTTPSession$py.class
HTTPSession.py
__init__.py
a5.py
aar.py
acl.py
aioobe.py
ant.py
atl.py
caps.py
cont.py

brian


-----Original Message-----
From: jyt...@li...
[mailto:jyt...@li...]On Behalf Of John E.
Conlon
Sent: Monday, March 19, 2001 4:22 PM
To: jyt...@li...
Subject: [Jython-users] How to call external commands


Hi Jython users,

I would like to replace my bat and sh startup scripts with jython py
scripts.  But after experimentation I can not figure out how to call
external executables in my underlying system. =20

Have seen comments that the os.system(name) command is not yet
implemented.
 Is there any other way to launch external programs without the
os.system
command?

thanks for any suggestions,

John

_______________________________________________
Jython-users mailing list
Jyt...@li...
http://lists.sourceforge.net/lists/listinfo/jython-users

[Jython-users] How to call external commands

[John E. C. <jc...@ve...>]

Hi Jython users,

I would like to replace my bat and sh startup scripts with jython py
scripts.  But after experimentation I can not figure out how to call
external executables in my underlying system.  

Have seen comments that the os.system(name) command is not yet implemented.
 Is there any other way to launch external programs without the os.system
command?

thanks for any suggestions,

John

[Jython-users] Jython GUI debugger/IDE

[Kexx <ke...@in...>]

I've given up trying to make Idle (from Python) work with Jython (no =
TkInter module).
I can edit the files using it, of course, but I would like to debug in =
GUI mode, and do the rest of the wonderful things the IDE supports.

Any alternatives I should consider?
I use JDK 1.3 on Win2k, without "X Window System", so DDD frontends =
won't work, I guess...

Should I bear with pdb?


Best regards,
Juris.

P.S. I would appreciate replys to ke...@in... if at all possible =
(sourceforge mailinglists confuse me).

[Jython-users] Storing code objects

[Jim A. <ji...@tr...>]

Question:

How do I comvert a compiled code object to some kind of bytestream?
'Pickle' can't handle PyCode ("can't pickle ...PyTableCode object"), and
PyCode is not serializable. Am I missing something or is there no way to
do this easily?

Backround:

I am prototyping a program that uses Jython to allow users to design
forms by entering Jython expressions which are evaluated based on a
large set of XML data that is 'scoped' into the PythonInterpreter
beforehand. (Example: 'Customer.Name' or 'for p in Customer.Phones:
print p') We have built a GUI that displays the forms and allows entry
of the expressions, the 'definition' of the form is stored in XML along
with Fonts, justification, and other formatting info. After each
expression is evaluated the result is 'massaged' using various Java
routines to build a complete page.

The previous version used JavaScript (Rhino) but I'm trying to switch it
to Python to make it easier for the form designers.

I'm having a problem, though, with the speed: when interpreting
expressions Jython is half the speed of Rhino: this is critical for this
app.

I timed the compile compared the the 'eval' and found the compile takes
90% of the time:

 PyCode code = __builtin__.compile(evalLine, "<string>", "eval");  //
90%

 PyObject result = python.eval( (PyCode)code );                    //
10% !!

If I could store the compiled 'code objects' within the forms somehow I
think I could increase the speed of the forms 10x, but I can't figure
out a way to get some kind of 'bytestream' of the code object.

-- 
                                 __o
Jim Adrig                      _ \<,_
ji...@tr...          ' `/ ' `
                  ___________ `-'  `-'

Flon's Law:
        There is not now, and never will be, a language in
        which it is the least bit difficult to write bad programs.

Re: [Jython-users] Python Library Modules Not Included in Jython Distribution

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

Hi, um... Uncle Roastie (Ron),

[Uncle Roastie]
> In my reading on JPython/Jython, I came across a comment
> that said many of the Python Library modules are not included
> in the Jython distribtion for installation.  It then says that you
> can easily download these missing modules yourself from
> the Jython home page.  So I started looking for the missing modules,
> but was unsuccessful in my search.

The JPython distribution used to be released without the libs, and the
libs could be downloaded separately on the JPython site- that could be
what the comment referred to.  Also, as Jython's Lib directory was
growing, it was suggested that getting the libs from CPython
to "try and see what worked" was a good idea.  CPython's libs are in my
Jython path, so maybe the reference was to the CPython modules
(www.python.org).  In other words, there isn't really extra libraries
to be downloaded from the Jython site at this time.  For libraries
not included with Jython, look to the CPython module library (if the
module itself is not written in C that is).

Regards,
Robert

[Jython-users] Java Executing Jython

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

I'm trying to have my Java code execute existing
Jython code.  When I compile the code using javac, I get a compiler =
error
that says it doesn't recognize the class PythonInterpreter (see =
<=3D=3D=3D).


CLASSPATH:  has the JDK, the jython.jar, my Jython application jar
PATH:  has the JVM

   import org.python.util.PythonInterpreter;
   import org.python.core.*;

  import SomeJavaClass;

   public class MyJavaClass
   {
        public void SomeMethod (void)
        {
         PythonInterpreter interp =3D new PythonInterpreter(); // =
<=3D=3D=3D=3D=3D=3D=3D=3D compiler error
         SomeJavaClass javaVar =3D null;
         // java statements, handled in Python
         interp.exec("import MyJythonModule"); =20
         interp.exec("javaVar =3D MyJythonModule.someMethod()");
         javaVar =3D (SomeJavaClass)interp.get("javaVar", =
SomeJavaClass);

      } // end SomeMethod

  } // end class MyJavaClass

Any ideas would be appreciated.

Ron

ron...@ne... (W)
ro...@ro... (H)

[Jython-users] Python Library Modules Not Included in Jython Distribution

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

In my reading on JPython/Jython, I came across a comment
that said many of the Python Library modules are not included
in the Jython distribtion for installation.  It then says that you
can easily download these missing modules yourself from
the Jython home page.  So I started looking for the missing modules,=20
but was unsuccessful in my search.

Any hints/pointers would be appreciated.

Ron

ron...@ne... (W)
ro...@ro... (H)

[Jython-users] Re: Pretty cool

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

[Moved to jython-users]

[John A. Tenney]

>We have developed a machine controller written in Java (with real-time
>portions in C++), and are looking for a good language that allows scripting
>our application. We have found Jython to be great for this, in general, but
>have some performance concerns. Currently, we call
>"InterativeConsole.push(String)" to download our code (including functions),
>line by line to the Jython environment.

That's strange. And by strange, I don't mean the performance problem you
are seing, but your use of the interpreter <wink>.

The push() method is only intended for interactive use where the user
are actually typing each line. If you already have your entire script,
the PythonInterpreter.exec() and PythonInterpreter.execfile() are much
faster.

>Then we can invoke the functions
>just by calling the function name. When I load a Jython function, does it
>get interpreted to some intermediate form that executes faster, or is every
>line always parsed every time it is executed?

Each call to push() will attempt to compile the entire script. Many
times the compilation will fail because the script isn't complete yet.

The exec and execfile methods will compile the string/file only once.

An example:

--------------- si4.java --------------- 
import java.util.*;

import org.python.core.*;
import org.python.util.*;

public class si4 {
    public static void main(String[] args) {
        PythonInterpreter interp = new PythonInterpreter();
        interp.execfile("si4.py");

        interp.exec("foo(42)");
        interp.get("foo").__call__(new PyString("hello world"));
    }
}

--------------- si4.py --------------- 
def foo(value):
    print "now in foo. Value is", value


The java program loads the script "si4.py" and all the module symbols
that the script defines will be available in the PythonInterpreter
namespace. Then the "foo" function is called twice. The first call uses
exec which is the simplest to use but it is also the slowest. The second
call to "foo" uses an explicit lookup and call and is a lot faster.

>Also, we find that our functions can have no full line comments; if they do,
>when we push the comment line, it interprets it as an "end of function".

An artifact of using push().

>Is there any list that we can subscribe to for Jython users?

The jython-users list:

   http://lists.sourceforge.net/lists/listinfo/jython-users

regards,
finn

Re: [Jython-users] GUI for Jython

[D-Man <ds...@ri...>]

On Thu, Mar 15, 2001 at 10:00:18AM +0100, Georg Umgiesser wrote:
| 
| Hallo,
| 
| I like the idea of using Jython in parallel with Python. However,
| I did not find any message in the Jython homepage on GUI's.
| What GUI's are supported? Is Tkinter supported?

To support Tkinter, you would need access to compiled C code.  I think
CPython does this by calling into the tcl interpreter to execute the
Tk code (but I'm not 100% sure).  Jython only has access to Java
stuff, unless you use JNI to give Java access to C stuff.  You could
make Tkinter (or any other toolkit like PyGTK or wxPython) accessible,
but it would be a pain and require JNI.

Actually, if you like GTK, there are already Java bindings, and Jython
connects Python to Java very seamlessly.  Of course, that would
require having GTK on the system, which means dealing with C binaries.
One of the nice features of Python and Java is system independce,
except for the interpreter itself.

-D

[Jython-users] GUIs for Jython

[Daniel L. <da...@br...>]

Georg,

AWT and Swing (Java GUI) are supported very well. Use those. The advantage
is that you can use a free Java IDe to design your GUI and then import (i.e.
cut and paste in the Jython source--Tkinter eat your heart out  wishing for
a graphical designer ;-) I use free ones try JBuilder, Net Beans, or
Sun--all offer reasonably complete IDes in free versions.

Good luck.

Daniel Lord
da...@br...

[Jython-users] Jython scripting in dbXML

[Tom B. <bra...@db...>]

For anyone who cares, I've written a quick and dirty class that allows
Python scripting (via Jython) within the dbXML server.  This module is
not officially supported by the dbXML Group, but may be in the future. 
I'm spread rather thin lately, so if anyone wants to pick up the
development of this piece, I'd appreciate it.

You can find the Python module at http://www.tbradford.org/
More info for dbXML can be found at http://www.dbxml.org/

Thanks,
Tom

Fwd: RE: [Jython-users] DnD in Jython

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

Already sent to syKim:

>
>
>syKim,
>
>>Thank you very much, Ype  :)
>>
>>I saw your code and it was very helpful..
>>
>>Now, I'm got the idea of translation DnD in Java
>>
>>I'll try more translation for it.. Thank you.
>
>My pleasure.
>
>>However, According to your mention as below:
>>>Since you have some Java code already, you can subclass it
>>>in Jython (Just as JTree is subclassed here), so
>>>there is no need to rewrite existing Java code into Jython.
>>
>>It's possible that import .java source file?
>>
>>I thought that only .py can be imported...
>>
>>How import .java source file?  just import as impoting .py or other way on
>>it?
>
>Compile the .java file to a .class file, and make sure the directory
>of the class file is part of the java class path when you invoke
>jython. Then have a look at:
>
>http://www.jython.org/docs/usejava.html
>
>and enjoy the miracles of dynamic method invocation, class
>attribute access and subclassing in jython.
>
>Have fun,
>Ype