cymake

Cython is hybrid C-Python language to easily write Python C-extensions. Cython allows one to write fast Python-ish code and easily integrate C or C++ code.

This repository has CMake utilities for building Cython projects with CMake and is an improvement of simplification of the already existent *cython-cmake-example` https://github.com/thewtex/cython-cmake-example with a hierarchy of C++ classes and usage of C++ STL containers and iterators, which is not very clear from the Cython doc.

The features of this build system include:

Easy configuration of build settings.
Easy integration of external libraries.
Implicit Makefile dependency generation for .pxd files.
Implicit Makefile dependency generation for C/C++ headers.
Out-of-source builds.

This simple project needs to be built with CMake > 2.6 and the latest version of cython (currently 0.17.1).

It explains how to do some interesting wrapping of C++ class hierarchies with Cython and how to get a Python module from them without too much pain.

Again thanks to the Matthew McCormick and his cython-cmake-example https://github.com/thewtex

Source Download & Compilation

First, acquire the source code by cloning the git repository:

git clone https://github.com/CarloNicolini/cymake.git

then follow the instructions here.

Build on Linux

In order to build this project in a Ubuntu/Linux box you have to install:

1. gcc/g++ compiler and all its related libraries ( sudo apt-get install build-essential )

2. cmake > 2.6 (I suggest downloading the latest CMake from www.cmake.org rather than relying on the repositories)

3. cython > 0.17 ( download it from http://cython.org/ otherwise if the repositories are up-to-date, make the usual sudo apt-get install cython )

You can try to build this project as follows: first enter the base directory

cd cymake

then issue the command

cmake .

(I suggest to make a Debug build of it, by explicitly specifying cmake -DCMAKE_BUILD_TYPE=Debug . ) The output text of cmake should be something similar to:

-- The C compiler identification is GNU
-- The CXX compiler identification is GNU
-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Found Cython: /usr/local/bin/cython 
-- Found PythonLibs: /usr/lib/libpython2.7.so 
-- Configuring done
-- Generating done
-- Build files have been written to: /home/user/cymake

The module test1.so will then be built inside cymake/build folder.

You can make a simple test of the test1.so module either loading it as it were a usual python module, on an interactive python shell:

$> python
Python 2.6.6 (r266:84292, Sep 15 2010, 16:22:56) 
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from test1 import pyQux as Qux
q=Qux()
q.methodcall()

or by directly calling your script or the examples/test1.py python script.

python test1.py

which should make the call of the methocall method of the class Qux and show the output of it.

In this little project you have to carefull choose the name of things. I choose the naming convention which sets the python wrappers of class X as pyX. Then when importing the module is better to import it using the as keyword in python, for example, here the C++ class Qux is wrapped in test1.pyx as pyQux. When I import it, is renamed in Qux as follows:

from test1 import pyQux as Qux

This convention helps you to distinguish the C++/Python classes in your project.

Build on OSX

The code is also tested on OSX with Cython, CMake and g++ installed. In order to get the latest cython version on OSX I warmly suggest to use MacPort version of it, because Fink version of cython is currently 0.16. The steps to follow are the same of the Linux version.