How to use “pycimport” module of Jython?

Question

I want to import a pyc file in Jython, and I was suggested to explore the 'pycimport' module in Jython, but since this is an experimental module, I was not able to get any code examples, I would be very glad if anybody can help me to implement this module in Java.

Answer 1

Why do you want to implement the pycimport module in Java?

Using the pycimport module is actually quite simple, you just import the module, and after that you can import modules in pyc-files:

cole:tmp tobias$ cat mymodule.py
def fibonacci(n):
    a,b = 1,0
    for i in range(n):
        a,b = a+b,a
    return a

cole:tmp tobias$ python
Python 2.7 (r27:82508, Jul  3 2010, 21:12:11) 
[GCC 4.0.1 (Apple Inc. build 5493)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from mymodule import fibonacci
>>> fibonacci(4)
5
>>> fibonacci(5)
8
>>> ^D
cole:tmp tobias$ ls mymodule.*
mymodule.py mymodule.pyc
cole:tmp tobias$ mv mymodule.py xmymodule.pyx
cole:tmp tobias$ jython
Jython 2.5.2rc4 (trunk:7202, Feb 24 2011, 14:31:12) 
[Java HotSpot(TM) 64-Bit Server VM (Apple Inc.)] on java1.6.0_26
Type "help", "copyright", "credits" or "license" for more information.
>>> import pycimport
>>> from mymodule import fibonacci
>>> fibonacci(4)
5
>>> fibonacci(5)
8
>>> ^D

Just to show that pycimport does infact import from the pyc-file:

cole:tmp tobias$ jython
Jython 2.5.2rc4 (trunk:7202, Feb 24 2011, 14:31:12) 
[Java HotSpot(TM) 64-Bit Server VM (Apple Inc.)] on java1.6.0_26
Type "help", "copyright", "credits" or "license" for more information.
>>> import mymodule
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named mymodule
>>> import pycimport              
>>> import mymodule 
>>> mymodule.__file__
'mymodule.pyc'
>>> ^D

As you note though, the pycimport module is experimental. I don't think anyone has touched it since I wrote it 4 years ago. A few things have changed in the Jython internals that pycimport uses since then, so there might be a few issues in it. It could be fun to revisit that code, but I don't know when I would have time, so I will not make any promises.

Answer 2

This is how I did it:)

The pyc file named shams.pyc is located at C:\PyTest\ and its corresponding.py file's contents are as follows:

shams.py

class test:

    def call_helloworld(self) :
        return "Hello World"

test.java

import org.python.core.PyObject;
import org.python.core.PyString;
import org.python.util.PythonInterpreter;

import org.python.core.PyObject;
import org.python.core.PyString;
import org.python.util.PythonInterpreter;
public class test{ 
    public static void main(String[] args) {
        PythonInterpreter interpreter = new PythonInterpreter();
        PythonInterpreter.initialize(System.getProperties(),System.getProperties(), new String[0]); 
        interpreter.exec("import sys");
        interpreter.exec("sys.path.append('C:\\PyTest')"); 
        interpreter.exec("import pycimport");
        interpreter.exec("import shams");
        interpreter.exec("from shams import test");
        PyObject pyClass = interpreter.get("test");
        PyString real_result = (PyString) pyClass.invoke("call_helloworld",pyClass.__call__());
        System.out.println(real_result);
    }
}