How to embed python interpreter that can use PySide2 to interact with widgets created in C++?

[veracioux]

Hello,
I am creating a python plugin system for my Qt5 C++ application. I'm using pybind11 to embed the python interpreter into my app. I would like plugins to be able to add custom PySide2 widgets to already existing C++ widgets. While doing that, I have to respect the following requirements:

• No dependencies other than PySide2 or PyQt5 (prefer the former) on the python side, and no linking to additional libraries besides pybind11 and the libpython library
• No binding generation using shiboken, though I'm willing to accept shiboken as a dependency if need be
• No converting parts of my application into a standalone library

I have managed to create a QApplication in C++ and it is available inside python, so I can add top-level widgets to my application just fine. But I don't know how my python module can interact with widgets created in C++.

Here's an example application to illustrate what I want:

• In C++ I create a window, set a vbox layout and add a button to the layout.
• I import a custom module called mymodule using the embedded interpreter, thereby executing the module
• mymodule creates a PySide2 QPushButton and adds it to the layout that was created on the C++ side

C++ code (main.cpp):

#include <pybind11/embed.h>
#include <QApplication>
#include <QPushButton>
#include <QVBoxLayout>
#include <QWidget>

namespace py = pybind11;

int main(int argc, char* argv[]) {
    py::scoped_interpreter guard{};

    QApplication app(argc, argv);
    auto window = new QWidget();
    auto cppButton = new QPushButton("C++ button");

    auto layout = new QVBoxLayout(window);
    layout->addWidget(cppButton);

    window->show();

    // Executes mymodule in the current directory
    auto module = py::module_::import("mymodule");
    return app.exec();
}

Python code in ./mymodule.py:

from PySide2.QtWidgets import QPushButton
pythonButton = QPushButton('Python button')
# How can I obtain a reference to 'layout' that was created in C++, so the following is possible:
layout.addWidget(pythonButton)

Is what I'm asking even possible?

[SGaist]

Hi,

I think you will be interested by the scriptable application example in PySide's sources.

[J.K.Who]

Struggling in the same matter... Have you solved it?