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extradoc / blog / draft / cffi-release-0.1.rst

CFFI release 0.1


We're pleased to announce the first public release, 0.1 of CFFI, a way to call C from Python. (This release does not support PyPy yet --- but we announce it here as it is planned for the next release :-)

The package is available on bitbucket as well as documented. You can also install it straight from the python package index (pip).

The aim of this project is to provide a convenient and reliable way of calling C code from Python. The interface is based on LuaJIT's FFI and follows a few principles:

  • The goal is to call C code from Python. You should be able to do so without learning a 3rd language: every alternative requires you to learn their own language (Cython, SWIG) or API (ctypes). So we tried to assume that you know Python and C and minimize the extra bits of API that you need to learn.
  • Keep all the Python-related logic in Python so that you don't need to write much C code (unlike CPython native C extensions).
  • Work either at the level of the ABI (Application Binary Interface) or the API (Application Programming Interface). Usually, C libraries have a specified C API but often not an ABI (e.g. they may document a "struct" as having at least these fields, but maybe more). (ctypes works at the ABI level, whereas native C extensions work at the API level.)
  • We try to be complete. For now some C99 constructs are not supported, but all C89 should be, including macros (and including macro "abuses", which you can manually wrap in saner-looking C functions).
  • We attempt to support both PyPy and CPython (although PyPy support is not complete yet) with a reasonable path for other Python implementations like IronPython and Jython.
  • Note that this project is not about embedding executable C code in Python, unlike Weave. This is about calling existing C libraries from Python.

Status of the project

Consider this as a beta release. Creating CPython extensions is fully supported and the API should be relatively stable; however, minor adjustements of the API are possible.

PyPy support is not yet done and this is a goal for the next release. There are vague plans to make this the preferred way to call C from Python that can reliably work between PyPy and CPython.

Right now CFFI's verify() requires a C compiler and header files to be available at run-time. This limitation will be lifted in the near future and it'll contain a way to cache the resulting binary.

Cheers, Armin Rigo and Maciej Fijałkowski