Introduction

• This is a tiny example of combining C++ code with Python and build with CMake, On C++ side, it currently only has 1 function int add(int x, int y); which is then wrapped to a python module using PyBind11, and can be imported by python using import pyCPP.

Install

• First, clone the repo: git clone https://github.com/bznick98/try-pyCPP.git
• Go to root directory of try-pyCPP: cd try-pyCPP

On MacOS/Ubuntu:

• Need to have CMake installed.
  • If CMake not installed:
    • MacOS: brew install cmake
    • Ubuntu: sudo apt-get -y install cmake
• Run pip install . Under the directory try-pyCPP/
• Done and ready to be imported. (It will install in the global python environment)

On Windows:

• TODO: Figure out what exactly are needed to install in Windows.
• I installed Visual Studio 2019 with C++ extension, which includes CMake and some other necessary tools.
• Install the python module by
  • python3 setup.py develop --user
  • Done if no error occurs, ready to be imported.
• Alternative Method (Cleaner):
  • Create a virtual environment by python3 -m venv venv/
  • Enter the virtual environment by ./venv/Scripts/Activate.ps1
  • If success, prompt will change starting with (venv)
  • Install pyCPP by pip install .
  • Done and pyCPP should be able to import now.
  • Exit virtual environment by deactivate whenever done using the module.

Potential Problems During Installation

• If CMake not installed:
  • MacOS: brew install cmake
  • Ubuntu: sudo apt-get -y install cmake
• If on Ubuntu: Fatal error: Python.h: No such file or Directory
  • Install python3-dev by running apt-get install python3-dev

Run & Test

• After successful install, you should be able to import pyCPP just like using any other python modules.
• There is only 1 sample function pyCPP.add(x,y) which takes two int arguments and add them up.
• Example Use:

  import pyCPP
  pyCPP.add(20,30)

  • The program should print out a statement and a result.

To Uninstall / Remove Package:

• On MacOS/Linux:
  • run pip uninstall pyCPP
  • OR run sh rmbuild.sh if you used python3 setup.py to install.
• On Windows: Haven't figured it out where the package was installed.

The installation has tested on:

• MacOS 10.15.5
• Ubuntu 16.04
• Windows 10