# scripting-cpython

**Repository Path**: mirrors_scijava/scripting-cpython

## Basic Information

- **Project Name**: scripting-cpython
- **Description**: A scripting engine based on "real" Python [UNMAINTAINED]
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-09-25
- **Last Updated**: 2025-12-21

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# (Native) Python Scripting

This library provides a
[JSR-223-compliant](https://en.wikipedia.org/wiki/Scripting_for_the_Java_Platform)
scripting plugin for [Python](http://www.python.org/). In contrast to the
[Jython support](https://github.com/scijava/scripting-jython), this library
accesses CPython (i.e. native Python) via JNI.

It is implemented as a `ScriptLanguage` plugin for the [SciJava
Common](https://github.com/scijava/scijava-common) platform, which means that
in addition to being usable directly as a `javax.script.ScriptEngineFactory`,
it also provides some functionality on top, such as the ability to generate
lines of script code based on SciJava events.

For a complete list of scripting languages available as part of the SciJava
platform, see the
[Scripting](https://github.com/scijava/scijava-common/wiki/Scripting) page on
the SciJava Common wiki.

## How to build in Eclipse (requires at least Eclipse Luna)

Please note that a C compiler needs to be found via the command-line and that
`python.h` needs to be found by the compiler.

With these prerequisites in place, it should be as simple as
*File>Import>Maven>Existing Maven Project...*.

You might want to make sure that *target/nar/nar-generated* is added as
a source directory to the project (if not, you might need to restart Eclipse).
This directory is generated by the [NAR plugin](http://maven-nar.github.io/).

## Running from Python
As things stand now, scripting-cpython relies on your installed version of
Python and the [javabridge package](http://pythonhosted.org/javabridge/).
You can install javabridge using PIP - the installation instructions are
documented at the page referenced by the link above.

As an example, here's how to start ImageJ 2.0 from Python:

* Unzip the ImageJ application.
* Put the scripting-cpython JAR in the application's `jars` folder

Now assuming that you have the application in `/foo/ImageJ.app` and the
library that maven compiled for you in `/bar/lib`, the following script
will launch ImageJ with CPython scripting support:

    import os
    import javabridge
    path_imagej = "/foo/ImageJ.app/jars"
    jars = [os.path.join(path_imagej, x)
            for x in os.listdir(path_imagej):
            if x.endswith(".jar")]
    lib_path = os.environ["PATH"]+";/bar/lib"
    library_path_arg = "-Djava.library.path=%s" % lib_path
    javabridge.start_vm([library_path_arg], class_path=javabridge.JARS+jars)
    javabridge.activate_awt()
    env = javabridge.get_env()
    jargs = env.make_object_array(0, env.find_class("java/lang/String"))
    runnable = javabridge.run_script("""
        new java.lang.Runnable() {
         run: function () {
             Packages.net.imagej.Main.launch(args);
         } };""", dict(args=jargs))
    javabridge.execute_runnable_in_main_thread(runnable)

  You should be able to start a script editor from `File->New->Script...` and
  then choose `CPython` from the language menu and you should be good to go.

## The scripting language

Inputs to your script are either translated to Python native types or,
if they are Java types, they are wrapped using reflection. You can import
classes into your local scope using `importClass`. Here is an example:

    importClass("java.lang.Integer")
    Integer.toString(Integer.MAX_VALUE) # returns 2^31 - 1

and another:

    importClass("java.util.ArrayList")
    a = ArrayList()
    a.add("Hello")
    a.add("World")
    str(a) # returns [ Hello, World ]

If you want to wrap an object retrieved from the javabridge, you can use
JWrapper:

     import javabridge
     a = JWrapper(javabridge.make_instance("java/util/ArrayList", "()V"))
     a.add("Hello")
     a.add("World")
     str(a.size()) # returns 2