boost::python examples

These are a few examples on how to use the boost::python library to extend Python with C++ libraries. Some of the are based on the existing tutorial for boost::python from Joel de Guzman. Others are independent.

Prerequisites

general

• CMake (>= 2.8.3)
• Boost (tested with 1.4.2, but should work with >= 1.3.2)
• Python (tested with 2.7, but should work with >= 2.2)
• a C++ compiler for your platform, e.g. GCC or MinGW

The examples should work on Linux, Windows and Mac, but currently have not been tested under Windows.

Mac OS X with homebrew

There is a special package needed called boost-python. The standard boost package will not be recognized by cmake.

• brew install cmake boost-python

Furthermore, for the homebrew python lib to be used, its path must be provided to cmake. This is handled in the build.sh script, but for reference, or if any issues arise, that can be done manually as follows (substitute the path as appropriate for your Python version):

cmake -DPYTHON_LIBRARY=/usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/lib/libpython2.7.dylib ..

Building

• Set the BOOST_ROOT environment variable if Boost is installed in a non-standard directory
• create a build directory, e.g. directly in the project directory and cd to it: mkdir build ; cd build
• run cmake .. and afterwards make

Alternatively, run the provided build.sh script.

Tests

All examples contain tests, but these only try to run the examples without checking the output. Their purpose is mainly to make sure that compilation works and produces valid Python modules.

Python 3

The code works with Python 3 both on Linux and on OS X. However, there are several caveats.

Linux

• Build Boost::Python against Python 3 (needs at least version 1.56.0)
• make sure python resolves to python3 (e.g., by using a python3 VE)
• run cmake -DBOOST_ROOT=xxx ..

OS X (again with homebrew)

Some effort has been made to make Python 3 compilation automatic, by making modifications to build.sh and CMakeLists.txt that account for quirks on the Apple platform regarding cmake, paths, and naming conventions for python/python3. Having said that, if you use build.sh, then you will still need to do the following:

• Build Boost::Python against Python 3 (needs at least version 1.56.0)
• make sure python resolves to python3 (e.g., by using virtualenv)

If you are building without build.sh, then you will additionally need to:

• run cmake -DBOOST_ROOT=xxx -DPYTHON_LIBRARY=xxx -DPYTHON_INCLUDE_DIR=xxx ..
• As of the time of this writing, the naming convention is that python2 is called "python" and python3 is called "python3" on the Apple platform. Therefore, in CMakeLists.txt verify that the line FIND_PACKAGE(Boost COMPONENTS python) is changed to FIND_PACKAGE(Boost COMPONENTS python3).

1. How make building

• pre-requsisite: https://stackoverflow.com/questions/42123509/cmake-finds-boost-but-the-imported-targets-not-available-for-boost-version update cmake to 3.11.3 to avoid running issue:

Boost 1.63 requires CMake 3.7 or newer. Boost 1.64 requires CMake 3.8 or newer. Boost 1.65 and 1.65.1 require CMake 3.9.3 or newer. Boost 1.66 requires CMake 3.11 or newer. Boost 1.67 is only supported by CMake master since March 2018.

• on orlando's local computer

1. generate makefile

$ cmake -DBoost_INCLUDE_DIRS=/usr/local/opt/boost/icnlude -DBoost_LIBRARIES=/usr/local/opt/boost-python3/lib:/usr/local/opt/boost/lib  -DPYTHON_LIBRARY=~/miniconda3/lib/libpython3.6m.dylib -DPYTHON_INCLUDE_DIR=~/miniconda3/include/python3.6m

2. build

$ make

refer to : https://stackoverflow.com/questions/15929566/need-help-getting-started-with-boost-python

issue: "vtable for boost::python::objects::py_function_impl_base", referenced from: boost::python::objects::py_function_impl_base::py_function_impl_base() in hello.cpp.o NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.