jython-users

[Jython-users] [Q] newbie's question on Jython

[Young-Jin L. <yl...@ui...>]

Hi, all.=20
I have a question on the imbedded Jython. It seems like that a Java =
application can use a Jython as an interpreter module, but I'm not sure =
what kind of things can be done with the imbedded Jython. For example, =
can a Java application call a user-defined Python method through a =
Jython interpreter? If it cannot be done, is there any other way to do =
this? I need a Java interpreter module....
Thanks in advance.

Young-Jin Lee

Re: [Jython-users] [Q] newbie's question on Jython

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

On Tue, 21 Aug 2001, Young-Jin Lee wrote:
> Hi, all.
> I have a question on the imbedded Jython. It seems like that a Java
> application can use a Jython as an interpreter module, but I'm not sure
> what kind of things can be done with the imbedded Jython.

Anything you can do in Jython can be done with the embedded interpreter.

> For example,
> can a Java application call a user-defined Python method through a
> Jython interpreter?

Yes, with ease.

> If it cannot be done, is there any other way to do
> this?

Using the embedded interpreter is best.

> I need a Java interpreter module....

Here's an example...

import java.util.Properties;
import org.python.util.PythonInterpreter;

public class embeddingExample {

    protected PythonInterpreter interp;

    public static void main(String[] args) {
        embeddingExample embed = new Embedding();
        embed.startInterp();
        embed.test();
    }

    protected void startInterp() {
        Properties props = new Properties();

        if (System.getProperty("python.home") == null)
            props.put("python.home", "/usr/local/jython");

        PythonInterpreter.initialize(preProps, postProps, argv);
        interp = new PythonInterpreter();
    }

    public void useInterp() {
        // define and call a Jython function
        interp.exec("def test(message):\n" +
                    "    print message");
        interp.exec("test('Hello world')");

        // you can import Python modules as use them just as easily
        interp.exec("import glob\n" +
                    "print glob.glob('*')");

    }
}



Enjoy,
Robert

Re: [Jython-users] [Q] newbie's question on Jython

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

The example I sent has at least 2 errors that need corrected.

   error 1- The "embed.test()" line should read "embed.useInterp()".

   error 2- the initialize arguments are wrong

corrections noted below.

sorry about that.

On Tue, 21 Aug 2001, Robert W. Bill wrote:
>
> import java.util.Properties;
> import org.python.util.PythonInterpreter;
>
> public class embeddingExample {
>
>     protected PythonInterpreter interp;
>
>     public static void main(String[] args) {
>         embeddingExample embed = new Embedding();
>         embed.startInterp();
>         // embed.test();       <-- ERROR
          embed.useInterp(); //  <-- CORRECTION
>     }
>
>     protected void startInterp() {
>         Properties props = new Properties();
>
>         if (System.getProperty("python.home") == null)
>             props.put("python.home", "/usr/local/jython");

          //CORRECTED initialize method here
          PythonInterpreter.initialize(System.getProperties(), props,
                                       new String[0]);
>         interp = new PythonInterpreter();
>     }
>
>     public void useInterp() {
>         // define and call a Jython function
>         interp.exec("def test(message):\n" +
>                     "    print message");
>         interp.exec("test('Hello world')");
>
>         // you can import Python modules as use them just as easily
>         interp.exec("import glob\n" +
>                     "print glob.glob('*')");
>
>     }
> }

RE: [Jython-users] [Q] newbie's question on Jython

[Alan L. <al...@li...>]

In addition to the use of interp.exec(), interp.eval() can be used to return
values back to the Java side -- however you'll have to dig around a bit in
the API docs for PyObject, PyInstance, PyTuple etc to learn how to get the
underlying Java object out of the returned, wrapped, data. I've got Jython
running a Java-based web server whose servlets (JSP) call into Jython to do
dynamic evaluation of elements in a database which return Python objects to
the servlets which then strip out the Java goodies to generate pages --- all
works crisply and reliably.

Alanl


-----Original Message-----
From: jyt...@li...
[mailto:jyt...@li...]On Behalf Of Robert W.
Bill
Sent: Tuesday, August 21, 2001 9:53 AM
To: Young-Jin Lee
Cc: jyt...@li...
Subject: Re: [Jython-users] [Q] newbie's question on Jython


On Tue, 21 Aug 2001, Young-Jin Lee wrote:
> Hi, all.
> I have a question on the imbedded Jython. It seems like that a Java
> application can use a Jython as an interpreter module, but I'm not sure
> what kind of things can be done with the imbedded Jython.

Anything you can do in Jython can be done with the embedded interpreter.

> For example,
> can a Java application call a user-defined Python method through a
> Jython interpreter?

Yes, with ease.

> If it cannot be done, is there any other way to do
> this?

Using the embedded interpreter is best.

> I need a Java interpreter module....

Here's an example...

import java.util.Properties;
import org.python.util.PythonInterpreter;

public class embeddingExample {

    protected PythonInterpreter interp;

    public static void main(String[] args) {
        embeddingExample embed = new Embedding();
        embed.startInterp();
        embed.test();
    }

    protected void startInterp() {
        Properties props = new Properties();

        if (System.getProperty("python.home") == null)
            props.put("python.home", "/usr/local/jython");

        PythonInterpreter.initialize(preProps, postProps, argv);
        interp = new PythonInterpreter();
    }

    public void useInterp() {
        // define and call a Jython function
        interp.exec("def test(message):\n" +
                    "    print message");
        interp.exec("test('Hello world')");

        // you can import Python modules as use them just as easily
        interp.exec("import glob\n" +
                    "print glob.glob('*')");

    }
}



Enjoy,
Robert


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