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Have you ever tried Cython? It's always seemed cool to me, so I've always planned on using that if I ran into a case where I needed (relatively) direct C librar

Have you ever tried Cython? It's always seemed cool to me, so I've always planned on using that if I ran into a case where I needed (relatively) direct C library access or wanted to speed things up beyond what straight Python is capable of.

xaa 9y ago
Sure. I use it for some things and straight C++ for others. Cython is good for simple things, like small tight loops. One thing that is much more reliable in pure C++ is any kind of threading or OpenMP etc. Theoretically Cython has it, in practice it can cause very weird problems. Also if you want to use C (or C++) libs in Cython, you have to manually declare all the function prototypes before using them. Also Cython has a tendency to make minor breaking changes to syntax every version, breaking my code and/or making it version-dependent. Since I distribute to others, the best method for linking performance intensive-code to Python I have found is: 1. Write the core in C++ 2. extern "C" a simple C API for it 3. Compile both to a SO 4. Access the SO from ctypes It is more robust than Cython IME. Another advantage of this approach is that you have now have a generic C library you can use anywhere else if you want, not just Python. And you don't have to link -lpython so the C lib can be used in places where Python isn't installed. Finally, it can be nice to have some C++ binaries for startup time, and AFAIK you can't compile binaries with setuptools.
- actuallyalys 9y ago
  Thank you for your very informative answer!
aldanor 9y ago
If you're into both C++ and Python, I recommend pybind11 [1] - Cython is a crutch and moreover C++ is not a first class citizen in it. For reasonably large codebases Cython just doesn't scale and debugging is a total nightmare. Disclaimer: I'm a contributor to pybind11. [1] https://github.com/pybind/pybind11 https://github.com/pybind/pybind11

xaa 9y ago

Sure. I use it for some things and straight C++ for others. Cython is good for simple things, like small tight loops. One thing that is much more reliable in pure C++ is any kind of threading or OpenMP etc. Theoretically Cython has it, in practice it can cause very weird problems. Also if you want to use C (or C++) libs in Cython, you have to manually declare all the function prototypes before using them. Also Cython has a tendency to make minor breaking changes to syntax every version, breaking my code and/or making it version-dependent. Since I distribute to others, the best method for linking performance intensive-code to Python I have found is: 1. Write the core in C++ 2. extern "C" a simple C API for it 3. Compile both to a SO 4. Access the SO from ctypes It is more robust than Cython IME. Another advantage of this approach is that you have now have a generic C library you can use anywhere else if you want, not just Python. And you don't have to link -lpython so the C lib can be used in places where Python isn't installed. Finally, it can be nice to have some C++ binaries for startup time, and AFAIK you can't compile binaries with setuptools.

actuallyalys 9y ago
Thank you for your very informative answer!

aldanor 9y ago

If you're into both C++ and Python, I recommend pybind11 [1] - Cython is a crutch and moreover C++ is not a first class citizen in it. For reasonably large codebases Cython just doesn't scale and debugging is a total nightmare. Disclaimer: I'm a contributor to pybind11. [1] https://github.com/pybind/pybind11 https://github.com/pybind/pybind11