Simple Jython script doesn't run from Java

Question

I am working on a big Java project, where Jython scripts are interpreted from Java code. For a reason I have not yet figured out, nothing works in the Jython script unless functions, class, variables, are declared all as global. In an attempt to track down this problem, I have narrowed the issue down to this. Below are :

A Jython script script.py which runs well when launched with java -jar jython.jar script.py
A Java main class Interpreter.java which uses Jython 2.2 methods to try and interpret the Jython script given above

Python script :

#global aFunction # uncommenting this makes the script work from Java

def main():
    aFunction()


def aFunction():
    print 'aFunction() called'


main()

Java class :

import java.io.File;

import org.python.core.PyException;
import org.python.core.PyStringMap;
import org.python.core.PySystemState;


public class Interpreter {

    public static void main(final String[] args) {
        final PyStringMap localNameSpace = new PyStringMap();
        final PyStringMap globalNameSpace = new PyStringMap();

        final File scriptFile = new File("../../jython/script.py");       
        PySystemState.initialize();

        try {
            org.python.core.__builtin__.execfile(scriptFile.getAbsolutePath(), globalNameSpace, localNameSpace);
        } catch (final PyException pyException) {
            pyException.printStackTrace();
        }

    }

}

Here is the error I get when running the Java class.

Traceback (innermost last):
  File "/opt/coflight/axel/workspace/essais/../../jython/script.py", line 12, in ?
  File "/opt/coflight/axel/workspace/essais/../../jython/script.py", line 5, in main
NameError: aFunction

Any ideas on how to correct the Java class so that the interpreter can run the Jython script ? Thanks !

mzjn · Accepted Answer · 2011-08-04 19:24:40Z

3

I can't explain the error that you get, but I was able to make it work by using PythonInterpreter:

org.python.util.PythonInterpreter interp = new org.python.util.PythonInterpreter();
String scriptname = "script.py"; 
interp.execfile(scriptname);

answered Aug 4, 2011 at 19:24

mzjn

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3 Comments

Axel Over a year ago

Yeah, that works for me as well ! I guess my application was supposed to use this rather than the call to __builtin__

Edwin Vivek N Over a year ago

Is there an option to do the same in scala?

mzjn Over a year ago

@EdwinVivekN: I'm not sure what you mean. You should ask a new question if you need help.

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