Method initPython

Engine/AppManager.cpp:2960–3043

void
AppManager::initPython()
{
#ifdef NATRON_RUN_WITHOUT_PYTHON

    return;
#endif
    //Disable user sites as they could conflict with Natron bundled packages.
    //If this is set, Python won’t add the user site-packages directory to sys.path.
    //See https://www.python.org/dev/peps/pep-0370/
    qputenv("PYTHONNOUSERSITE", "1");
    ++Py_NoUserSiteDirectory;

    //
    // set up paths, clear those that don't exist or are not valid
    //
    QString binPath = QCoreApplication::applicationDirPath();
    binPath = QDir::toNativeSeparators(binPath);
    NATRON_PYTHON_NAMESPACE::setupPythonEnv(binPath.toStdString());

    ///Must be called prior to Py_Initialize (calls PyImport_AppendInittab())
    initBuiltinPythonModules();
    
#if PY_MAJOR_VERSION >= 3
    _imp->mainModule = NATRON_PYTHON_NAMESPACE::initializePython3(_imp->commandLineArgsWide);
#else
    _imp->mainModule = NATRON_PYTHON_NAMESPACE::initializePython2(_imp->commandLineArgsUtf8);
#endif

    std::string err;
    std::string modulename = NATRON_ENGINE_PYTHON_MODULE_NAME;
    bool ok = NATRON_PYTHON_NAMESPACE::interpretPythonScript("import sys\nfrom math import *\nimport " + modulename, &err, 0);
    if (!ok) {
        throw std::runtime_error( tr("Error while loading python module %1: %2").arg( QString::fromUtf8( modulename.c_str() ) ).arg( QString::fromUtf8( err.c_str() ) ).toStdString() );
    }

    ok = NATRON_PYTHON_NAMESPACE::interpretPythonScript(modulename + ".natron = " + modulename + ".PyCoreApplication()\n", &err, 0);
    assert(ok);
    if (!ok) {
        throw std::runtime_error( tr("Error while loading python module %1: %2").arg( QString::fromUtf8( modulename.c_str() ) ).arg( QString::fromUtf8( err.c_str() ) ).toStdString() );
    }

    if ( !isBackground() ) {
        modulename = NATRON_GUI_PYTHON_MODULE_NAME;
        ok = NATRON_PYTHON_NAMESPACE::interpretPythonScript("import sys\nimport " + modulename, &err, 0);
        assert(ok);
        if (!ok) {
            throw std::runtime_error( tr("Error while loading python module %1: %2").arg( QString::fromUtf8( modulename.c_str() ) ).arg( QString::fromUtf8( err.c_str() ) ).toStdString() );
        }

        ok = NATRON_PYTHON_NAMESPACE::interpretPythonScript(modulename + ".natron = " +
                                                            modulename + ".PyGuiApplication()\n", &err, 0);
        assert(ok);
        if (!ok) {
            throw std::runtime_error( tr("Error while loading python module %1: %2").arg( QString::fromUtf8( modulename.c_str() ) ).arg( QString::fromUtf8( err.c_str() ) ).toStdString() );
        }

        //redirect stdout/stderr