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copied!<p>Interfacing Python with C/C++ is not an easy task.</p> <p>Here I copy/paste a <a href="https://stackoverflow.com/questions/456884/extending-python-to-swig-or-not-to-swig/456949#456949">previous answer</a> on a previous question for the different methods to write a python extension. Featuring Boost.Python, SWIG, Pybindgen...</p> <ul> <li><p>You can write an extension yourself in C or C++ with the <a href="http://docs.python.org/extending/index.html" rel="noreferrer">Python C-API</a>.</p> <p>In a word: don't do that except for learning how to do it. It's very difficult to do it correctly. You will have to increment and decrement references by hand and write a lot of code just to expose one function, with very few benefits.</p></li> <li><p><a href="http://www.swig.org/" rel="noreferrer">Swig</a>:</p> <p>pro: you can generate bindings for many scripting languages.</p> <p>cons: I don't like the way the parser works. I don't know if they've made some progress but two years ago the C++ parser was quite limited. Most of the time I had to copy/paste my .h headers to add some <code>%</code> characters and to give extra hints to the swig parser.</p> <p>I also needed to deal with the Python C-API from time to time for (not so) complicated type conversions. </p> <p>I'm not using it anymore. </p></li> <li><p><a href="http://www.boost.org/doc/libs/1_39_0/libs/python/doc/index.html" rel="noreferrer">Boost.Python</a>:</p> <p>pro: It's a very complete library. It allows you to do almost everything that is possible with the C-API, but in C++. I never had to write a C-API code with this library. I also never encountered a bug due to the library. Code for bindings either works like a charm or refuses to compile.</p> <p>It's probably one of the best solutions currently available if you already have some C++ library to bind. But if you only have a small C function to rewrite, I would probably try with Cython.</p> <p>cons: if you don't have a precompiled Boost.Python library you're going to use Bjam (sort of a replacement of make). I really hate Bjam and its syntax.</p> <p>Python libraries created with B.P tend to become obese. It also takes a <strong>lot</strong> of time to compile them.</p></li> <li><p><a href="http://sourceforge.net/projects/pygccxml/?source=dlp" rel="noreferrer">Py++</a>: it's Boost.Python made easy. Py++ uses a C++ parser to read your code and then generates Boost.Python code automatically. You also have a great support from its author (no it's not me ;-) ).</p> <p>cons: only the problems due to Boost.Python itself.</p> <p><strong>Edit</strong> this project looks discontinued. While probably still working it may be better to consider switching.</p></li> <li><p><a href="http://code.google.com/p/pybindgen/" rel="noreferrer">Pybindgen</a>:</p> <p>It generates the code dealing with the C-API. You can either describe functions and classes in a Python file, or let Pybindgen read your headers and generate bindings automatically (for this it uses pygccxml, a python library wrote by the author of Py++).</p> <p>cons: it's a young project, with a smaller team than Boost.Python. There are still some limitations: you cannot expose your own C++ exceptions, you cannot use multiple inheritance for your C++ classes. </p> <p>Anyway it's worth trying!</p></li> <li><p>Pyrex and <a href="http://www.cython.org/" rel="noreferrer">Cython</a>:</p> <p>Here you don't write real C/C++ but a mix between Python and C. This intermediate code will generate a regular Python module. </p></li> </ul> <p><strong>Edit Jul 22 2013:</strong> Now Py++ looks discontinued, I'm now looking for a good alternative. I'm currently experimenting with Cython for my C++ library. This language is a mix between Python and C. Within a Cython function you can use either Python or C/C++ entities (functions, variables, objects, ...). </p> <p>Cython is quite easy to learn, has very good performance, and you can even avoid C/C++ completely if you don't have to interface legacy C++ libraries.</p> <p>However for C++ it comes with some problems. It is less "automagic" than Py++ was, so it's probably better for stable C++ API (which is now the case of my library). The biggest problem I see with Cython is with C++ polymorphism. With Py++/boost:python I was able to define a virtual method in C++, override it in Python, and have the Python version called within C++. With Cython it's still doable but you need to explicitly use the C-Python API.</p> <p><strong>Edit 2017-10-06:</strong></p> <p>There is a new one, <a href="https://github.com/pybind/pybind11" rel="noreferrer">pybind11</a>, similar to Boost.Python but with some potential advantages. For example it uses C++11 language features to make it simpler to create new bindings. Also it is a header-only library, so there is nothing to compile before using it, and no library to link. </p> <p>I played with it a little bit and it was indeed quite simple and pleasant to use. My only fear is that like Boot.Python it could lead to long compilation time and large libraries. I haven't done any benchmark yet.</p>

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