Python in Perl, natively

Work in progress! Be warned!

This project is a little thing I'm playing with to allow Perl to natively call Python as a library. It has access to the C functions that implement the Python language API.

How to use it

There's an example in example.pl that shows how to use it. Here it is:

use Python::FFI;
my $python = Python::FFI->new();

# Python: `import time`
# CPython: `PyImport_ImportModule()`

# Perl:
$python->import_importmodule('time');

You can see here that we are calling the CPython function that implements the import Python function.

What can I do with it?

Quite a few things. For example:

Run Python code natively in Perl
Run Python libraries natively in Perl
Implement your own python command line to Python. :)

Version of Python

Currently I'm supporting Python 3.7 since this is what my box currently installs. You might want to edit lib/Python/FFI.pm to remove the m if you don't have that variant.

If you edit it to a version of Python with a different public API functions, it's on you. :)

My purpose at the end is to always support the latest version.

Low-level details

Generating the API classes

The API classes are generated using two scripts:

find_funcs.pl: Run on the cpython.git clone. It generates the list of functions that Python has by analyzing the header files. The parsing is pretty crappy and it trips on a specific file and a set of functions there. The details at the beginning of the file explain how to overcome it.
create_classes.pl: Uses the JSON output of the previous file (which is included in the tools/ directory) and creates all the classes.

How it works

The Python::FFI uses Python::FFI::API which is a role that adds the functions under Py_ prefix. Those are the main Python functions not under a particular namespace.

The Python::FFI::API composes all the classes under API/. Each of these roles (as well as API.pm includes the specifications of the functions for that namespace.

The Python::FFI::Simple module is an interface to a set of higher-level methods I decide on that do not require knowing how to use the Python library. For example, if you want to use Python, you ahve to initialize and destruct the Python interpreter. With Python::FFI::Simple you don't need to. This does not match the Python API but provides a comfortable layer above it.

What needs to be done?

Right now this will not work for you. The reason is that I still haven't resolved all the function signatures. However...

Making it work for the demo

Edit lib/Python/FFI/API.pm and...
Under with remove everything except Python::FFI::API::Run
Under ffi_subs_data remove everything except Py_Initialize and Py_FinalizeEx
Edit lib/Python/FFI/API/Run.pm and...
Under ffi_subs_data remove everything except PyRun_SimpleString
Depending on your Python version, edit lib/Python/FFI.pm's ffi_lib

If you make these changes, the example.pl will work fine.

xsawyerx/python-ffi