Jython

[ Eric Jain ]
> I'm just stuck with exactly the same problem, an interpreter that is
> created from within a "web start" application can't find any Java
> classes.
> 
> The only workaround I found (and that actually works) was:
> 
>     interpreter = new PythonInterpreter();
>     interpreter.set("Entry", Entry.class);
>     ...
>     interpreter.exec("e = Entry()"); // OK
> 
> But having over a hundred classes, this is not a really feasible
> solution.
> Any suggestions would be appreciated!

You could try to add java packages, either from python:
  import sys
  sys.add_package("your.package")
or from java (example from PyServlet.java):
  PySystemState sys = Py.getSystemState();
  sys.add_package("javax.servlet");
  sys.add_package("javax.servlet.http");
  sys.add_package("javax.servlet.jsp");
  sys.add_package("javax.servlet.jsp.tagext");

Best wishes,
Oti.

__________________________________________________
Do you Yahoo!?
U2 on LAUNCH - Exclusive greatest hits videos
http://launch.yahoo.com/u2

> You could try to add java packages, either from python:
>   import sys
>   sys.add_package("your.package")
> or from java (example from PyServlet.java):
>   PySystemState sys = Py.getSystemState();
>   sys.add_package("javax.servlet");
>   sys.add_package("javax.servlet.http");
>   sys.add_package("javax.servlet.jsp");
>   sys.add_package("javax.servlet.jsp.tagext");

Thanks...

Unfortunately neither solution seems to fix the problem completely, as the
following statement doesn't seem to do anything:

    from org.test import *

Apparently class names have to be listed explicitly:

    from org.test import A, B, C

Which is a bit of a problem when working with a large amount of classes...


--
Eric Jain

[ Eric Jain ]
> > You could try to add java packages, either from python:
> >   import sys
> >   sys.add_package("your.package")
> > or from java (example from PyServlet.java):
> >   PySystemState sys = Py.getSystemState();
> >   sys.add_package("javax.servlet");
> >   sys.add_package("javax.servlet.http");
> >   sys.add_package("javax.servlet.jsp");
> >   sys.add_package("javax.servlet.jsp.tagext");
> 
> Thanks...
> 
> Unfortunately neither solution seems to fix the problem completely,
> as the
> following statement doesn't seem to do anything:
> 
>     from org.test import *
Just don't do this if org.test is a java package.

> Apparently class names have to be listed explicitly:
> 
>     from org.test import A, B, C
This is the recommended way.

Best wishes,
Oti. 

__________________________________________________
Do you Yahoo!?
U2 on LAUNCH - Exclusive greatest hits videos
http://launch.yahoo.com/u2

> >     from org.test import A, B, C
> This is the recommended way.

Just noticed another disadvantage of having to do so: This doesn't allow
lazy loading of classes by Java Web Start, i.e. all classes are always
downloaded, even if they are never used.


--
Eric Jain

Quoting Eric Jain <Eric.Jain@...>:

> > >     from org.test import A, B, C
> > This is the recommended way.
> 
> Just noticed another disadvantage of having to do so: This doesn't allow
> lazy loading of classes by Java Web Start, i.e. all classes are always
> downloaded, even if they are never used.
>

Eric - I'm new to the world of http://java.sun.com/products/javawebstart/.

I thougth all the jars mentioned in the <resources> section were downloaded
before the program started.   Then these jars become the classpath for the
program.   Isn't this the case?

Is there a way to get jython to load needed jars from a URL at runtime?   It
would be great if sys.path could contain URLs.... has anyone done this?

I think jython + java webstart is a combination with great potential.   I
haven't quite figured out how to use classes from JARs that are not in the stock
jython & java distributions.   Do you have examples of how to do this?

My example is at http://mattpayne.org/jython/p2.jnlp
(http://mattpayne.org/jython/p2_jnlp.txt to see what my XML file looks like). 
It's just the embedding example from Chapter 12 of Jython Essentials from
ora.com.   Instead of loading embed.py from the local filesystem, I load it from
a URL using a simple java class.

You can see all the source if you go to http://mattpayne.org/jython

-Matt

> I thougth all the jars mentioned in the <resources> section were
> downloaded before the program started.   Then these jars become
> the classpath for the program.   Isn't this the case?

    <package name="org.x.*" part="a" recursive="true"/>
    <jar href="tools.jar" part="a" download="lazy"/>

This will only download tools.jar when a class such as org.x.Y is used for
the first time. Unfortunately, when running Jython from a Java application
that was launched through Web Start, classes have to be imported explicitely
before you can use them:

    PySystemState state = Py.getSystemState();
    state.add_package("org.x");

    from org.x import Y

Which, in this case, causes tools.jar to be downloaded, even if it is
never used afterwards...


--
Eric Jain