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Details

scalapy.python.library/nativeLibrary

Name of the Python shared library, i.e the Python shared library file name (e.g libpython3.9m.dylib, libpython3.7.so) without the lib prefix and the file extension.

The Python shared library take the form of python{ldversion} where ldversion is {major}.{minor}{abiflags}. There are 2 ways to get the name of the Python shared library

from sysconfig import get_config_var

ldversion = get_config_var("LDVERSION")

python_native_lib = f"python{ldversion}"

or

from sys import abiflags
import sysconfig

version = sysconfig.get_python_version()

python_native_lib = f"python{version}{abiflags}"

We went with the 2nd method since it is more portable.

jna.library.path/nativeLibraryPaths

The directory where the Python shared library lives. It is located in either f"{sys.base_prefix}/lib" or config dir sysconfig.get_config_var('LIBPL'). For each Python installation, which one of these 2 directories actually contains the shared library is almost arbitrary. We decided to just use both with priority given to the config dir f"{sysconfig.get_config_var('LIBPL')}:{sys.base_prefix}/lib".

scalapy.python.programname/executable

The path to the Python interpreter executable, used as the input to Py_SetProgramName. The Python doc recommends running Py_SetProgramName prior to Py_Initialize so that the correct Python run-time libraries relative to the interpreter executable can be found (prefix, exec_prefix, ...)

https://docs.python.org/3/extending/embedding.html#very-high-level-embedding https://docs.python.org/3/c-api/init.html#c.Py_SetProgramName

This enables using ScalaPy with virtualenv. Since a Python installation inside virtualenv shares the same shared library (libpython...so) with the base installation, without Py_SetProgramName, there's no way to point ScalaPy towards the runtime directories set by virtualenv.

import sys

sys.executable

ldflags

The recommended linker options for embedding the Python interpreter into another application, mostly extracted from the outputs of

pythonX.Y-config --ldflags for python 3.7 and

pythonX.Y-config --ldflags --embed for python 3.8+,

with added library paths from nativeLibraryPaths

https://docs.python.org/3/extending/embedding.html#compiling-and-linking-under-unix-like-systems

The full path to pythonX.Y-config is f"{sys.base_prefix}/bin/python{ldversion}-config".