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

Re: [Jython-dev] A new FAQ-entry

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

Maybe we should provide better support for this (?).

[ Janusch Waclawczyk]
> I wanted to create a new entry to a FAQ, but I failed:
> 
> 3.8. How can I create 2-dimen. Java arrays from jython?

The following works (not that intuitive):
>>> from java.lang import String,Object
>>> from jarray import array
>>> a=array(["a","b"],String)
>>> a
array(['a', 'b'], java.lang.String)
>>> # this is wrong:                             
>>> b=array([a,a],type(a)) # or a.__class__
>>> b
array([array(['a', 'b'], java.lang.String), array(['a', 'b'], 
java.lang.String)], org.python.core.PyArray)
>>> # this works !
>>> b=array([a,a],Object.getClass(a))
>>> b
array([array(['a', 'b'], java.lang.String), array(['a', 'b'], 
java.lang.String)], [Ljava.lang.String;) 
>>> 
# [Ljava.lang.String; is the java internal name for (class) type 
#  java.lang.String[]
# b is a (jython side) java.lang.String[][]

regards, Samuele Pedroni

PS: If there's a simpler way, I don't remember.

[Jython-dev] A new FAQ-entry

[Janusch W. <Jan...@ic...>]

Hello,

I wanted to create a new entry to a FAQ, but I failed:

3.8. How can I create 2-dimen. Java arrays from jython?
I would like to create String[][] array to use it as an argument
for a java method, but the jarray.array(...) creates only 1-dimen.
arrays.
Any suggestion?

Regards
Janusz Waclawczyk

[Jython-dev] namespace examples and java classloading

[Kiran R K. <ki...@al...>]

hi.. can you point out to me  some examples of setting the namespace using
the PythonInterpreter(Pydict ) constructor ? I cant seem to find any.
Also, can you point out the mechanism by which jython, (when embedded and
called from a java app) finds and loads its java classes ? I want some
java classes to be loaded by default when jython starts up, rather than
doing "import foo from bar" in the .py scripts. Is there an API to do this
or do I have to rely on the $CLASSPATH variable which the java program
reads on startup.In the event of the java program using another
classloader to load its classes,$CLASSPATH wont do for me...

any help would be appreciated...
thanx

p.s. thanx to brian zimmer for his previous reply :-)

A fair exterior is a silent recommendation.
		-- Publilius Syrus

[Jython-dev] Operator overloading

[Richard D. <rdy...@bt...>]

A useful feature is operator overloading, which is present in Python but 
absent in Java. Given that Jython is written in Java, is operator 
overloading available in Jython?

Richard

-------------------------------
Richard Dybowski, 143 Village Way, Pinner, Middlesex  HA5 5AA, UK
Tel (mobile): 079 76 25 00 92

[Jython-dev] [ jython-Patches-403918 ] fixes to bugs #122819 #122847 #131507 #126677

[nobody <no...@so...>]

Patches #403918, was updated on 2001-02-20 20:59
You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=312867&aid=403918&group_id=12867

Category: None
Group: None
Status: Closed
Priority: 5
Submitted By: ian west
Assigned to: Nobody/Anonymous
Summary: fixes to bugs #122819 #122847 #131507 #126677

Initial Comment:
#131507 stack overflow in simple class ---- unimplemented abstract methods now throw AttributeError
#126677 Throwing IndexError from __getitem__() ---- now throws IndexError
#122819  Multi-level Java method overriding fails --- now works as required
#122847 Can't acces public member of package in private base class -- added python.security.matchJavaAccess
             to registry

----------------------------------------------------------------------

Comment By: Finn Bock
Date: 2001-03-05 12:06

Message:
Logged In: YES 
user_id=4201

The fixes to 131507 & 126677 are not correct and can't be 
applied as is.

The fix to 122819 is really clever and have been applied.

IMO the fix to 122847 & the new registry entry should be 
independent of respectJavaAccessibility.

----------------------------------------------------------------------

Comment By: ian west
Date: 2001-02-20 22:00

Message:
the statement: "import ucar.netcdf.AttributeSet;" needs to be deleted from the top of the PyJavaClass.java file.

Ooops!
ianzsk


----------------------------------------------------------------------

You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=312867&aid=403918&group_id=12867

[Jython-dev] [ jython-Patches-403419 ] Reworked coercion model

[nobody <no...@so...>]

Patches #403419, was updated on 2001-01-25 11:59
You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=312867&aid=403419&group_id=12867

Category: None
Group: None
Status: Closed
Priority: 5
Submitted By: Finn Bock
Assigned to: Nobody/Anonymous
Summary: Reworked coercion model

Initial Comment:
This is a work-in-progress and there may be some additional cruft that I'll remove later. Added as a patch in order to get some feedback from others who have made their own number types. The patch, as it stand right now, require that existing number types must be rewritten to work under new coercion model.

----------------------------------------------------------------------

Comment By: Finn Bock
Date: 2001-03-05 12:01

Message:
Logged In: YES 
user_id=4201

Added the patch almost as is.

----------------------------------------------------------------------

You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=312867&aid=403419&group_id=12867

[Jython-dev] Who uses Jython

[<pyl...@ya...>]

Hi,

The company I am working for is carrying out a huge
SAP implementation for its operations in Europe.
I amusing Jython to access IBM MQSeries (Middleware
Tranport Package) through its java API. I explore the
API with Jython before writing Java Code.
I also write MQSeries administration scripts and
utilities directly in Jython. It is amazingly faster
and easier than writing them in C or Java.
Jython is great, Thanks guys.

Pierre-Yves Lesage

____________________________________________________________
Do You Yahoo!?
Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk
or your free @yahoo.ie address at http://mail.yahoo.ie

[Jython-dev] re.match() problem

[Brian Z. <bri...@ya...>]

C:\Python20>python
ActivePython 2.0, build 202 (ActiveState Tool Corp.)
based on Python 2.0 (#8, Oct 19 2000, 11:30:05) [MSC 32 bit (Intel)] on
win32
Type "copyright", "credits" or "license" for more information.
>>> import re
>>> w = 'MixedCaseWord'
>>> m = re.match(r'\b([A-Z][a-z]+){2,}\b', w)
>>> m
<SRE_Match object at 008005C0>
>>> m.group(0)
'MixedCaseWord'

While using jython-cvs with -Dpython.home=C:\jython-2.0

C:\jython-cvs>jython
Jython 2.1pre-a1 on java1.3.0 (JIT: null)
Type "copyright", "credits" or "license" for more information.
>>> import re
>>> w = 'MixedCaseWord'
>>> m = re.match(r'\b([A-Z][a-z]+){2,}\b', w)
>>> m
>>> m.group(0)
Traceback (innermost last):
  File "<console>", line 1, in ?
AttributeError: 'None' object has no attribute 'group'
>>>

Anything I'm missing? is there a difference in re syntax? or is this a bug?

Thanks,

/Brian

Re: [Jython-dev] no errno module in jython?

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

[Brian Zhou]

>>>> import stat
>>>> dir(stat)
>['ST_ATIME', 'ST_CTIME', 'ST_DEV', 'ST_GID', 'ST_INO', 'ST_MODE',
>'ST_MTIME', 'ST_NLINK', 'ST_SIZE', 'ST_UID', 'S_ENFMT', 'S_IEXEC',
>'S_IFBLK', 'S_IFCHR', 'S_IFDIR', 'S_IFIFO', 'S_IFLNK', 'S_IFMT',
>'S_IFREG', 'S_IFSOCK', 'S_IMODE', 'S_IREAD', 'S_IRGRP', 'S_IROTH',
>'S_IRUSR', 'S_IRWXG', 'S_IRWXO', 'S_IRWXU', 'S_ISBLK', 'S_ISCHR',
>'S_ISDIR', 'S_ISFIFO', 'S_ISGID', 'S_ISLNK', 'S_ISREG', 'S_ISSOCK',
>'S_ISUID', 'S_ISVTX', 'S_IWGRP', 'S_IWOTH', 'S_IWRITE', 'S_IWUSR',
>'S_IXGRP', 'S_IXOTH', 'S_IXUSR', '__doc__', '__file__', '__name__']
>>>> import errno
>Traceback (innermost last):
>  File "<console>", line 1, in ?
>ImportError: no module named errno
>
>It's not a problem by itself in jython, but I want make the following
>code portable between python and jython, and am wondering if the errno
>module can be added to the standard jython installation.
>
><         if os.name == 'nt':
><             try:
><                 os.remove(new_filename)
><             except OSError, er:
><                 if er.errno <> errno.ENOENT: raise er
><         os.rename(tmp_filename, new_filename)

While portability have my fullest attention, I really don't know what
values we should give the fields in the "errno" module. The raise
statements in javaos all set .errno to 0 because there are no
corresponding errno field in java.

The best solution I can suggest, is to add

   if os.name == 'java':

or

   if sys.platform[:4] == 'java':

to your code.

regards,
finn

[Jython-dev] no errno module in jython?

[Brian Z. <bri...@ya...>]

>>> import stat
>>> dir(stat)
['ST_ATIME', 'ST_CTIME', 'ST_DEV', 'ST_GID', 'ST_INO', 'ST_MODE',
'ST_MTIME', 'ST_NLINK', 'ST_SIZE', 'ST_UID', 'S_ENFMT', 'S_IEXEC',
'S_IFBLK', 'S_IFCHR', 'S_IFDIR', 'S_IFIFO', 'S_IFLNK', 'S_IFMT',
'S_IFREG', 'S_IFSOCK', 'S_IMODE', 'S_IREAD', 'S_IRGRP', 'S_IROTH',
'S_IRUSR', 'S_IRWXG', 'S_IRWXO', 'S_IRWXU', 'S_ISBLK', 'S_ISCHR',
'S_ISDIR', 'S_ISFIFO', 'S_ISGID', 'S_ISLNK', 'S_ISREG', 'S_ISSOCK',
'S_ISUID', 'S_ISVTX', 'S_IWGRP', 'S_IWOTH', 'S_IWRITE', 'S_IWUSR',
'S_IXGRP', 'S_IXOTH', 'S_IXUSR', '__doc__', '__file__', '__name__']
>>> import errno
Traceback (innermost last):
  File "<console>", line 1, in ?
ImportError: no module named errno

It's not a problem by itself in jython, but I want make the following
code portable between python and jython, and am wondering if the errno
module can be added to the standard jython installation.

<         if os.name == 'nt':
<             try:
<                 os.remove(new_filename)
<             except OSError, er:
<                 if er.errno <> errno.ENOENT: raise er
<         os.rename(tmp_filename, new_filename)

Thanks,

/Brian

Re: [Jython-dev] Re module status in CVS

[Brian Z. <bri...@ya...>]

[bzhou@server7 jython-cvs]$
/usr/java/jdk1.3/jre/bin/java -Dpython.home=/usr/local/jython-2.0 -class
path "./jython.jar" org.python.util.jython
Jython 2.1pre-a1 on java1.3.0 (JIT: null)
Type "copyright", "credits" or "license" for more information.
>>> import re
>>>

Mine works fine. "python.home" setting?

/Brian

----- Original Message -----
From: "Eli Ateljevich" <el...@ce...>
To: <jyt...@li...>
Sent: Friday, March 02, 2001 11:27 AM
Subject: [Jython-dev] Re module status in CVS


> Hi. At Finn's advice, I recently compiled the CVS version of Jython in
> order to use the new rich comparisons. They work great! However, I can
no
> longer "import re". I get
> ImportError: no module named re
>
> This module was recently a topic of some changes. Can someone explain
how
> to accommodate the recent changes?  .... or verify that these changes
are
> supposed to be invisible from the point of view of the user, so that I
can
> look for some other path issue?
> Thanks,
> Eli
>
>
> _______________________________________________
> Jython-dev mailing list
> Jyt...@li...
> http://lists.sourceforge.net/lists/listinfo/jython-dev
>

[Jython-dev] passing params to applet

[Mika, D. P (CRD) <mi...@ex...>]

Hello,

I am trying to pass an arg to an applet, but can't seem to get it to work--I get:

java.lang.NullPointerException
      at java.applet.Applet.getParameter(Applet.java:124)

What is wrong with this code?

Thanks

David Mika
mi...@cr...


from java import awt, applet

class HelloApplet(applet.Applet):
    def __init__(self):
        applet.Applet.__init__(self)
        print self.getParameter('param')

    def paint(self, g):
	g.setColor(awt.Color.black)
	g.fill3DRect(5,5,590,100,0)
	g.setFont(awt.Font('Arial', 0, 80))
	g.setColor(awt.Color.blue)
	g.drawString('Hello World', 90, 80)

if __name__ == '__main__':
    import pawt
    pawt.test(HelloApplet(),size=(800,200))

Re: [Jython-dev] Re module status in CVS

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

[Eli Ateljevich]

>Hi. At Finn's advice, I recently compiled the CVS version of Jython in 
>order to use the new rich comparisons. They work great! However, I can no 
>longer "import re". I get
>ImportError: no module named re
>
>This module was recently a topic of some changes. Can someone explain how 
>to accommodate the recent changes?  .... or verify that these changes are 
>supposed to be invisible from the point of view of the user, so that I can 
>look for some other path issue?

The CVS version does *not* contain any of the module that are a straight
copy of the CPython modules. Instead you will have to get a recent CVS
copy of CPython and use the modules there. Personally I have a setup
where my <home>/.jython contains:

python.path = i:\\python\\python\\dist\\src\\Lib

which is the directory where I have my CVS copy of CPython. This setup
works most of the time.

The "re" (actually the "sre") module is quite sensitive to the correct
synchronization between the the "_sre" module, which is part of jython
and the "re.py" module, which is part of CPython. At the moment the two
versions are synchronized so you should be able to use this combination
of Jython CVS and CPython CVS.

   http://sourceforge.net/cvs/?group_id=5470

regards,
finn

Re: [Jython-dev] [Fwd: installation problem]

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

Gerhard,
...
>then the first problem was gone but I ran into the next
>when I started the simple example program
>
>Maybe you can help me once more
>thank you
>gerhard
>
>
>gerhard@darkstar:~/work/prog/jython > jython Demo/awt/simple.py
>SIGSEGV   11*  segmentation violation
>        stackbase=0xbffff150, stackpointer=0xbfffefc4
>
>Full thread dump:
>    "Finalizer thread" (TID:0x40596210, sys_thread_t:0x412dae0c,
>state:R) prio=1
...

It looks like the java VM crashes during garbage collection, more
precisely: during finalization.

The first time you run jython after installation it
needs more memory because it initializes a package for each
jar file it finds. Increase memory and try again: use java -help
adapt the jython script.

As you are using a Pentium II and the default Suse JVM
the following may not apply:

I had the SIGSEGV problem using the blackdown JVM's on ppc, iirc
both versions 1.1.8 and 1.2.2
1.3 crashes in a more 'friendly' way: it gives up with an
out of memory error.

All this happens with the default 30Mb, but also with 160Mb of
memory.

Unfortunately the problem persists under 1.3: running a simple
python program can make the JVM give up quite regularly, but
in a seemingly random way, independent of the amount of memory
used.
I reported the problem to blackdown some time ago (for 1.2.2)
but I had no reaction. Since upgrading the 1.3 helps only a bit
I am considering moving to other hardware.

Please note that all this is on ppc. I have not heard of
similar problems on x86.

Good luck,
Ype

P.S. You might consider using the jython-user list for similar situations.

[Jython-dev] Re module status in CVS

[Eli A. <el...@ce...>]

Hi. At Finn's advice, I recently compiled the CVS version of Jython in 
order to use the new rich comparisons. They work great! However, I can no 
longer "import re". I get
ImportError: no module named re

This module was recently a topic of some changes. Can someone explain how 
to accommodate the recent changes?  .... or verify that these changes are 
supposed to be invisible from the point of view of the user, so that I can 
look for some other path issue?
Thanks,
Eli

[Jython-dev] [Fwd: installation problem]

[Gerhard S. <ger...@la...>]

Hallo,

thanks to your help I solved my first installation problem
were I hadn't set the classpath correct. I simple 
changed the jython script to:

java -Dpython.home=/home/gerhard/work/jython -classpath
"/home/gerhard/work/prog/jython/jython.jar:/usr/lib/java/lib/classes.zip:."
org.python.util.jython "$@"

then the first problem was gone but I ran into the next
when I started the simple example program

Maybe you can help me once more
thank you
gerhard


gerhard@darkstar:~/work/prog/jython > jython Demo/awt/simple.py 
SIGSEGV   11*  segmentation violation
        stackbase=0xbffff150, stackpointer=0xbfffefc4

Full thread dump:
    "Finalizer thread" (TID:0x40596210, sys_thread_t:0x412dae0c,
state:R) prio=1
    "Async Garbage Collector" (TID:0x40596258, sys_thread_t:0x412b9e0c,
state:R) prio
    "Idle thread" (TID:0x405962a0, sys_thread_t:0x41298e0c, state:R)
prio=0
    "Clock" (TID:0x40596088, sys_thread_t:0x41277e0c, state:CW) prio=12
    "main" (TID:0x405960b0, sys_thread_t:0x80891e0, state:R) prio=5
*current thread*
       
org.python.core.PyJavaClass.setBeanInfoCustom(PyJavaClass.java:575)
        org.python.core.PyJavaClass.init__dict__(PyJavaClass.java:139)
        org.python.core.PyJavaClass.initialize(PyJavaClass.java:101)
        org.python.core.PyJavaClass.init__bases__(PyJavaClass.java:199)
        org.python.core.PyJavaClass.initialize(PyJavaClass.java:100)
        org.python.core.PyJavaClass.init__bases__(PyJavaClass.java:199)
        org.python.core.PyJavaClass.initialize(PyJavaClass.java:100)
        org.python.core.PyJavaClass.init__bases__(PyJavaClass.java:199)
        org.python.core.PyJavaClass.initialize(PyJavaClass.java:100)
       
org.python.core.PyJavaClass.initConstructors(PyJavaClass.java:632)
        org.python.core.PyJavaClass.__call__(PyJavaClass.java:784)
        org.python.pycode._pyx0.f$0(simple.py)
        org.python.pycode._pyx0.call_function(simple.py)
        org.python.core.PyTableCode.call(PyTableCode.java:155)
        org.python.core.Py.runCode(Py.java:1055)
        org.python.core.__builtin__.execfile(__builtin__.java:288)
        org.python.core.__builtin__.execfile(__builtin__.java:292)
       
org.python.util.PythonInterpreter.execfile(PythonInterpreter.java:155)
        org.python.util.jython.main(jython.java:159)
Monitor Cache Dump:
    org.python.core.PyJavaClass@1079718592/1080470632: owner "main"
(0x80891e0, 2 ent
    org.python.core.PyJavaClass@1079718520/1080470376: owner "main"
(0x80891e0, 2 ent
    org.python.core.PyJavaClass@1079718304/1080470040: owner "main"
(0x80891e0, 3 ent
    org.python.core.PyJavaClass@1079718664/1080470888: owner "main"
(0x80891e0, 2 ent
Registered Monitor Dump:
    Verifier lock: <unowned>
    Thread queue lock: <unowned>
    Name and type hash table lock: <unowned>
    String intern lock: <unowned>
    JNI pinning lock: <unowned>
    JNI global reference lock: <unowned>
    BinClass lock: <unowned>
    Class loading lock: <unowned>
    Java stack lock: <unowned>
    Code rewrite lock: <unowned>
    Heap lock: <unowned>
    Has finalization queue lock: <unowned>
    Finalize me queue lock: <unowned>
    Dynamic loading lock: <unowned>
    Monitor IO lock: <unowned>
    Child death monitor: <unowned>
    Event monitor: <unowned>
    I/O monitor: <unowned>
    Alarm monitor: <unowned>
        Waiting to be notified:
            "Clock" (0x41277e0c)
    Monitor registry: owner "main" (0x80891e0, 1 entry)
Thread Alarm Q:
./jython: line 7:   826 Aborted                 java
-Dpython.home=/home/gerhard/work
/jython -classpath
"/home/gerhard/work/prog/jython/jython.jar:/usr/lib/java/lib/class
p:." org.python.util.jython "$@"


-------- Original Message --------
Subject: installation problem
Date: Tue, 27 Feb 2001 20:26:25 +0100
From: Gerhard Spitzlsperger <ger...@la...>
To: jyt...@li...

Hallo,

I just installed jython-20. Everything goes well
but when I start jython from the commandline
the following error appears:


gerhard@darkstar:~/work/prog/jython > jython
Unable to initialize threads: cannot find class java/lang/Thread
gerhard@darkstar:~/work/prog/jython > java -version
java version "1.1.8"
gerhard@darkstar:~/work/prog/jython > 

I use Linux SuSE 7.1 on a pentium II

maybe you can give me a hint.

Thank you
gerhard

RE: [Jython-dev] what do java interfaces mean?

[brian z. <bz...@zi...>]

> hi..im trying to call the PythonInterpreter() from within a java app, and
> run a python program.Since Python does not have *native* support for
> interfaces, what can I do after importing a java interface? Also,when I

After importing an interface, you can build a class implementing it as if it
was a class.

class myclass(someinterface):
 def callme(self, somearg):
  pass

> import code from java that does use interfaces(for e.g. Vector implements
> List,Map etc),the following code
> 	from java.util import Vector
> 	sim=Vector
> 	sim.addElement("first.py")
> throws an error TypeError: addElement(): expected 2 args; got 1

The reason you get the exception is because you are attempting to invoke the
method on the class Vector, rather than an instance of the class Vector.
You can fix this by:

>>> from java.util import Vector
>>> sim = Vector()
>>> sim.addElement("first.py")

My guess is it's not that an object implements an interface but that you are
not creating instances of classes.  In Java parlance, calling addElement as
you did above would work if addElement() was a static method.

>
> so what do I typecast the first argument to?
> 	sim.addElement(Vector,"fist")
> gives TypeError: addElement(): self arg can't be coerced to (well, it
> doesnt say what...)
>

The self arg is automatically passed to the method when a method is invoked
on an instance, not the class.

brian

[Jython-dev] what do java interfaces mean?

[Kiran R K. <ki...@al...>]

hi..im trying to call the PythonInterpreter() from within a java app, and
run a python program.Since Python does not have *native* support for
interfaces, what can I do after importing a java interface? Also,when I
import code from java that does use interfaces(for e.g. Vector implements
List,Map etc),the following code
	from java.util import Vector
	sim=Vector
	sim.addElement("first.py")
throws an error TypeError: addElement(): expected 2 args; got 1

so what do I typecast the first argument to?
	sim.addElement(Vector,"fist") 
gives TypeError: addElement(): self arg can't be coerced to (well, it
doesnt say what...)

any help would be appreciated :-)

ciao

RE: [Jython-dev] command-line install?

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

Well, if the command line install doesn't work, I've had success just
installing it elsewhere and then shipping the installed version down.
You'll have to change the paths in jython and jythonc on the target box
though.  

Wiser heads than me can say if that's a hack, but it's also been recommended
to me for commercial (pure) Java products by the vendor.

> -----Original Message-----
> From:	Gever Tulley [SMTP:Gev...@qu...]
> Sent:	Friday, March 02, 2001 4:34 AM
> To:	'jyt...@li...'
> Subject:	[Jython-dev] command-line install?
> 
> i'd like to run jython on a machine that I only have telnet access to and
> the
> jython-20 installer wants an X11 connection. any known solution?
> 
> 
> _______________________________________________
> Jython-dev mailing list
> Jyt...@li...
> http://lists.sourceforge.net/lists/listinfo/jython-dev

[Jython-dev] command-line install?

[Gever T. <Gev...@qu...>]

i'd like to run jython on a machine that I only have telnet access to and
the
jython-20 installer wants an X11 connection. any known solution?

RE: [Jython-dev] Py.java2py

[brian z. <bz...@zi...>]

Thanks for the input on checking sequences.  That's precisely the type of
information I was looking forward.  Is there any place where best practices
are written down?

I'll keep in mind your comments for the Python wrapper factory.  I like that
latter as well.

thanks,

brian

> -----Original Message-----
> From: jyt...@li...
> [mailto:jyt...@li...]On Behalf Of Finn Bock
> Sent: Wednesday, February 28, 2001 7:15 AM
> To: jyt...@li...
> Subject: Re: [Jython-dev] Py.java2py
>
>
> On Tue, 27 Feb 2001 07:30:57 -0600, you wrote:
>
> >The reason I ask is I have some code which wants to iterate an instance
> >using __len__ and __finditem__ magic methods on any sequence.
>
> Incidently, I hope you are aware that __len__ are allowed to lie. The
> only correct way to iterate over a sequence from java are:
>
>   PyObject item;
>   for (int i = 0; (item = seq.__finditem__(i)) != null; i++)
>     ;
>
> >I'll accept
> >anything with those two methods and I thought the Collection
> classes where
> >wrapped as such (thus my previous question about CollectionProxy; after
> >thinking about, it makes sense as to why Java classes come in as
> >PyJavaInstance instances.).  In the meantime I do this:
> >
> >protected boolean isSeq(PyObject object) {
> >	if(object instanceof PyJavaInstance) {
> >		List list = (List)object.__tojava__(List.class);
> >		if(list == Py.NoConversion) {
> >			return false;
> >		}
> >		object = new PyList((PyObject[])list.toArray(new
> PyObject[list.size()]));
> >	}
> >	return object.__findattr__("__finditem__") != null &&
> >object.__findattr__("__len__") != null;
> >}
>
> It should probably use __findattr__("__getitem__") if you want it to
> succeed on python classes with a "def __getitem__(self,idx):" method.
>
> OTOH, the best way of testing an objects sequence-ness is by indexing
> it:
>
>    protected boolean isSeq(PyObject object) {
>        try {
>            object.__finditem__(0);
>        } catch (PyException exc) {
>            return !Py.matchException(exc, Py.AttributeError);
>        }
>        return true;
>    }
>
> Generally the python language is very weak in this array. Jython's
> addition of java object does not improve the situation at all.
>
> >I'll look into writing the Java->Python wrapper factory and the
> developers
> >can do what they want with it.
> >
> >As for subclass support, would not Class.isAssignableFrom(Class) be
> >sufficient for handling these cases.    I'm thinking of this off
> the top of
> >my head so I'll have to test it out first.
>
> Indeed that would work.
>
> Implementation wise I can come up with two simple design. One use a
> hashtable where the subclass support is difficult to achive, the other
> use a list of two-tuples that is traversed sequentually where it is
> easy. I think the list is best, but only if it can be self-sorting:
>
> If a user add one wrapper for java.util.Vector and another for
> java.util.List, the Vector must be tested before the List in the list. I
> don't want the user to be concerned about this sequence.
>
> regards,
> finn
>
> _______________________________________________
> Jython-dev mailing list
> Jyt...@li...
> http://lists.sourceforge.net/lists/listinfo/jython-dev

[Jython-dev] Need your help

[Parvathini S G. <par...@mi...>]

Hi All,

  I am trying to download jython-20.class from the site=20
http://sourceforge.net/project/showfiles.php?group_id=3D12867. I can not =
able
to download the total 1.7 MB size after completion of the download.
Let me know if anyone of you have the alternative. Make sure i am
downloading this on Windows-2000.


Thanks in advance
Gangadhar

Re: [Jython-dev] Py.java2py

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

On Tue, 27 Feb 2001 07:30:57 -0600, you wrote:

>The reason I ask is I have some code which wants to iterate an instance
>using __len__ and __finditem__ magic methods on any sequence.

Incidently, I hope you are aware that __len__ are allowed to lie. The
only correct way to iterate over a sequence from java are:

  PyObject item;
  for (int i = 0; (item = seq.__finditem__(i)) != null; i++)
    ;

>I'll accept
>anything with those two methods and I thought the Collection classes where
>wrapped as such (thus my previous question about CollectionProxy; after
>thinking about, it makes sense as to why Java classes come in as
>PyJavaInstance instances.).  In the meantime I do this:
>
>protected boolean isSeq(PyObject object) {
>	if(object instanceof PyJavaInstance) {
>		List list = (List)object.__tojava__(List.class);
>		if(list == Py.NoConversion) {
>			return false;
>		}
>		object = new PyList((PyObject[])list.toArray(new PyObject[list.size()]));
>	}
>	return object.__findattr__("__finditem__") != null &&
>object.__findattr__("__len__") != null;
>}

It should probably use __findattr__("__getitem__") if you want it to
succeed on python classes with a "def __getitem__(self,idx):" method.

OTOH, the best way of testing an objects sequence-ness is by indexing
it:

   protected boolean isSeq(PyObject object) {
       try {
           object.__finditem__(0);
       } catch (PyException exc) {
           return !Py.matchException(exc, Py.AttributeError);
       }
       return true;
   }

Generally the python language is very weak in this array. Jython's
addition of java object does not improve the situation at all.

>I'll look into writing the Java->Python wrapper factory and the developers
>can do what they want with it.
>
>As for subclass support, would not Class.isAssignableFrom(Class) be
>sufficient for handling these cases.    I'm thinking of this off the top of
>my head so I'll have to test it out first.

Indeed that would work.

Implementation wise I can come up with two simple design. One use a
hashtable where the subclass support is difficult to achive, the other
use a list of two-tuples that is traversed sequentually where it is
easy. I think the list is best, but only if it can be self-sorting:

If a user add one wrapper for java.util.Vector and another for
java.util.List, the Vector must be tested before the List in the list. I
don't want the user to be concerned about this sequence.

regards,
finn

Re: [Jython-dev] installation problem

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

>Hallo,
>
>I just installed jython-20. Everything goes well
>but when I start jython from the commandline
>the following error appears:
>
>
>gerhard@darkstar:~/work/prog/jython > jython
>Unable to initialize threads: cannot find class java/lang/Thread

This happens when classes.zip (Java core classes) is not
on the class path in the jython script.
Check that classpath in the jython script includes
the directory java_directory/lib in the class path,
where java_directory is the directory for the java executable.

I had a similar problem under OS2 where I had to
patch the .bat files for jython and jythonc,
I now use .cmd REXX files I derived from these .bat files.

Regards, good luck,
Ype

[Jython-dev] installation problem

[Gerhard S. <ger...@la...>]

Hallo,

I just installed jython-20. Everything goes well
but when I start jython from the commandline
the following error appears:


gerhard@darkstar:~/work/prog/jython > jython
Unable to initialize threads: cannot find class java/lang/Thread
gerhard@darkstar:~/work/prog/jython > java -version
java version "1.1.8"
gerhard@darkstar:~/work/prog/jython > 

I use Linux SuSE 7.1 on a pentium II

maybe you can give me a hint.

Thank you
gerhard