Some features of the program, including importing dicom images, automatic computing of segmentations using the machine learning model, and computing of the surfaces of the segmentations, are implemented in Python. The C++ code calls the appropriate python scripts to perform these actions.
The Python scripts used by the program are located at src/python/scripts. This directory contains various py files.
Additionally, src/python/scripts/project_edition contains the package bms_project_edition from this repo which provides the machine learning and surfaces calculations features.
Our goal here is to document the management of the Python module search path (sys.path), which allows the python import instructions to correctly import these scripts when the program is executed.
When the program is installed, the program installation directory includes a python/ directory, and the scripts directory discussed above is copied into pyhton/scripts in the installation directory.
Initially, the Python module search path includes the python/ directory of the installation directory (see py_api.h).
At the beginning of the program, the function PyAPI::init() from init_python.h is called, which makes python run an import of python.scripts.__init__. This file contains code which makes python/scripts/project_edition being added to the Python search path. As a consequence, both python/ and python/scripts/project_edition are in the Python search path during the program execution.
The various scripts located at the root of python/scripts are able to import each other as they use relative imports.
The package bms_project_edition located in python/scripts/project_edition uses absolute imports, which correctly work as python/scripts/project_edition is in the Python search path.