Motivation

Extending Python with C++ is typically a painful process. It doesn't have to be. Tools such as runcython and protobuf make it easy to pass structured data from Python to C++ and gain massive performance improvements. Google's protobuf library encourages simple and maintanable interfaces between Python and C++ via fast serialization and deserialization of binary messages. The runcython command line utility considerably simplifies the build process for Cython, a static compiler for Python/Cython that makes wrapping C++ libraries a breeze.

In this example we pass an ObjectList protobuf message to a C++ function that prints its contents and returns the number of elements in the list. Each element in the ObjectList message is an Object message with two fields: name and id.

Usage

First, you need to install the following packages:

1. protobuf (https://developers.google.com/protocol-buffers/?hl=en)
2. runcython (https://github.com/Russell91/runcython)

Compile protobuf definition file for use by C++ and Python:

$ protoc -I=./ --python_out=./ --cpp_out=./ objlist.proto

Run Cython file:

$ runcython++ use_objlist.pyx '' "objlist.cpp objlist.pb.cc -lprotobuf"