Pyrex - a Language for Writing Python Extension Modules

Brief Description

Pyrex lets you write code that mixes Python and C data types any way you want, and compiles it into a C extension for Python.


About Pyrex

Language Overview


Contributed by Users

Quick Guide to Pyrex

Contributed by Michael JasonSmith.
If the above link doesn't work, there is a copy here.

Embedding Pyrex

Using Pyrex to write stand-alone programs that embed a Python interpreter.
Contributed by David McNab.

C++ Wrapping Tutorial

Contributed by David McNab. Warning: This page is really for Cython and mentions some Cython features that Pyrex doesn't have. Some of what it says is also obsoleted by recently-added C++ features in Pyrex.


Pyrex compiler and documentation

Pyrex-0.9.9.tar.gz (255272 bytes, 2010-04-12)

Test suite and testing framework

Pyrex-Tests-0.9.9.tar.gz (447472 bytes, 2010-04-12)
Note: Currently the testing framework will only work out of the box on MacOS X or Linux, but should be adaptable to other unices with a little work.

Release Notes for Version 0.9.9


Mercurial Repository and Updates

Previous Releases

Pyrex requires Python 2.3 or later, both to run the Pyrex compiler and to use the generated extension modules.


Version 0.9.9

Some features for interfacing with C++ code have been introduced, a few things have been changed, and some bugs have been fixed. See the Release Notes and CHANGES for details.

Old News


WARNING: I have not reviewed or tested these patches - use them at your own risk.

Sam Rushing has submitted a patch to Pyrex which adds some conditional compilation facilities.

Old Patches

Lenard Lindstrom contributed some patches to Pyrex to improve the C++ compatibility of the generated code. Since 0.9.4 these should no longer be necessary.


These packages are maintained by others, so they may not be up to date with the latest version.


Contributed by Giovanni Bajo

Fedora Core 1
Fedora Core 2
Contributed by Jan Ondrej


Contributed by Samuel Thibault

Related Tools

Generate HTML documentation from a compiled Pyrex module, by David McNab

Pyrex Builder X
A mini-IDE for building Pyrex projects on MacOSX, by Nik Molnar.

Mailing List

You are invited to subscribe to the Pyrex Mailing List for all Pyrex-related discussions.

Thanks are due to Johannes Grødem of Copyleft Software for setting up and hosting this list at the request of Joakim Ziegler.

Discussion of Pyrex is also welcome on the Python newsgroup, comp.lang.python.

IRC Channel #pyrex

I don't normally use IRC myself, but you may find someone there who's able to help you.


Greg Ewing ( )

Example Pyrex modules

#  Calculate prime numbers

def primes(int kmax):

  cdef int n, k, i
  cdef int p[1000]
  result = []
  if kmax > 1000:
    kmax = 1000
  k = 0
  n = 2
  while k < kmax:
    i = 0
    while i < k and n % p[i] <> 0:
      i = i + 1
    if i == k:
      p[k] = n
      k = k + 1
    n = n + 1
  return result

#  Defining an extension type

cdef class Spam:

  cdef int amount

  def __cinit__(self):
    self.amount = 0

  def get_amount(self):
    return self.amount

  def set_amount(self, new_amount):
    self.amount = new_amount

  def describe(self):
    print self.amount, "tons of spam!"