Using `pybind11` to Interface Python with C++: Part 1 - Installation

Introduction

pybind11 is an open-source Python binding library that allows you to operate modern C++11 in Python. It can wrap the C++ data types and methods as a callable Python module that creates seamless operability between C++ and Python.

Generally you will need Python bindings either because you want to use some C++ libraries in your Python programs, or because you want to create some Python test cases for your C++ projects. I first came to pybind11 because I wanted to test my neuroevolution algorithm on a classic Flappy Bird game.

In this series of posts I will provide a simple guide on how to create Python bindings for a C++ program. We will begin with the installation of pybind11 in this post as an appetizer.

Installing `pybind11` Using `conda`

We install pybind11 in the conda environment:

conda install -c conda-forge pybind11

Note pybind11 can be installed via pip:

pip3 install pybind11

However, I would not recommend this because pip will only install the necessary C++ headers but not the other files. When I was using cmake to include the pybind11 library externally, it gave the following error:

...

CMake Error at CMakeLists.txt:8 (find_package):
  By not providing "Findpybind11.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "pybind11",
  but CMake did not find one.

  Could not find a package configuration file provided by "pybind11" with any
  of the following names:

    pybind11Config.cmake
    pybind11-config.cmake

  Add the installation prefix of "pybind11" to CMAKE_PREFIX_PATH or set
  "pybind11_DIR" to a directory containing one of the above files.  If
  "pybind11" provides a separate development package or SDK, be sure it has
  been installed.

...

More details can be found in this discussion.

Installing `pybind11` from Source

Alternatively, we can also build pybind11 from source.

First clone the library from GitHub

git clone https://github.com/pybind/pybind11.git

Then build the project

cd pybind11
git checkout v2.4 # I use version v2.4
mkdir build && cd build
cmake ..
make

Finally, if make is successful, install the library:

make install

The following messages will be displayed during installation. pybind11 headers will be in installed in /usr/local/include/pybind11/; while cmake config files are in /usr/local/share/cmake/pybind11/.

Install the project...
-- Install configuration: "MinSizeRel"
-- Installing: /usr/local/include/pybind11
-- Installing: /usr/local/include/pybind11/attr.h
-- Installing: /usr/local/include/pybind11/embed.h
-- Installing: /usr/local/include/pybind11/numpy.h
-- Installing: /usr/local/include/pybind11/pybind11.h
-- Installing: /usr/local/include/pybind11/operators.h
-- Installing: /usr/local/include/pybind11/iostream.h
-- Installing: /usr/local/include/pybind11/chrono.h
-- Installing: /usr/local/include/pybind11/stl_bind.h
-- Installing: /usr/local/include/pybind11/buffer_info.h
-- Installing: /usr/local/include/pybind11/options.h
-- Installing: /usr/local/include/pybind11/functional.h
-- Installing: /usr/local/include/pybind11/stl.h
-- Installing: /usr/local/include/pybind11/detail
-- Installing: /usr/local/include/pybind11/detail/typeid.h
-- Installing: /usr/local/include/pybind11/detail/descr.h
-- Installing: /usr/local/include/pybind11/detail/internals.h
-- Installing: /usr/local/include/pybind11/detail/common.h
-- Installing: /usr/local/include/pybind11/detail/class.h
-- Installing: /usr/local/include/pybind11/detail/init.h
-- Installing: /usr/local/include/pybind11/common.h
-- Installing: /usr/local/include/pybind11/eval.h
-- Installing: /usr/local/include/pybind11/cast.h
-- Installing: /usr/local/include/pybind11/eigen.h
-- Installing: /usr/local/include/pybind11/pytypes.h
-- Installing: /usr/local/include/pybind11/complex.h
-- Installing: /usr/local/share/cmake/pybind11/pybind11Config.cmake
-- Installing: /usr/local/share/cmake/pybind11/pybind11ConfigVersion.cmake
-- Installing: /usr/local/share/cmake/pybind11/FindPythonLibsNew.cmake
-- Installing: /usr/local/share/cmake/pybind11/pybind11Tools.cmake
-- Installing: /usr/local/share/cmake/pybind11/pybind11Targets.cmake

Introduction

Installing pybind11 Using conda

Installing pybind11 from Source

FEATURED TAGS

Installing `pybind11` Using `conda`

Installing `pybind11` from Source