How to embed Python3 with the standard library

Question

I am attempting to embed Python in an (ultimately multiplatform) C++ app.

It\'s important that my app contains its own Python implementation (in the same way that blend

Answer 1

Since this doesn't really have an answer, I will offer this for posterity. I also do not have access to a Mac, so it may be a little different for you than on Linux. Also, the required dependencies must be installed for this to work, but that is usually easy enough to figure out.

Create a working directory

mkdir ~/embeddedpython
cd ~/embeddedpython

Download the Python source

wget https://www.python.org/ftp/python/3.6.1/Python-3.6.1.tgz

Create an installation directory for Python

mkdir ./installation

Extract the downloaded source files

tar xvf Python-3.6.1.tgz

Enter the newly created source directory

cd Python-3.6.1

Configure Python to install in our installation directory

./configure --prefix="/home//embeddedpython/installation"

Make and install Python

make && make install

Go back to your working directory

cd ..

Create a new PYTHONHOME directory where the library will reside

mkdir home && mkdir home/lib

Copy the Python library to our new home directory

cp -r ./installation/lib/python3.6 ./home/lib/

Create a new c++ source file (embeddedpython.cpp) with the following code taken from the python documentation, with the exception of the setenv function call.

#include 
#include 

int main(int argc, char *argv[])
{
    setenv("PYTHONHOME", "./home", 1);

    wchar_t *program = Py_DecodeLocale(argv[0], NULL);
    if (program == NULL) {
        fprintf(stderr, "Fatal error: cannot decode argv[0]\n");
        exit(1);
    }
    Py_SetProgramName(program);  /* optional but recommended */
    Py_Initialize();
    PyRun_SimpleString("from time import time,ctime\n"
                       "print('Today is', ctime(time()))\n");
    if (Py_FinalizeEx() < 0) {
        exit(120);
    }
    PyMem_RawFree(program);
    return 0;
}

Compile and run

g++ embeddedpython.cpp -I ./installation/include/python3.6m/ ./installation/lib/libpython3.6m.a  -lpthread -ldl -lutil
./a.out

> Today is Fri Apr 14 16:06:54 2017

From here on it is standard embedded python as usual. With this method, the "home" directory must be included in your deployment, and the environment variable PYTHONHOME must be set to point to it before any python related code is executed.