test failures definitely seem related?

Re: test failures

The semantics of

@tacaswell @anntzer do you have a fundamental understanding of the _may_allow_interrupt() context manager? You have written the former/latter calls. Do we really want the context manager take QApplication and QEventLoop respectively? If so, that should be documented.

I've now "fixed" this PR by checking hasattr(qapp, "allWindows") before trying to close any windows, but that feels like fixing symptoms.

Do we really want the context manager take QApplication and QEventLoop respectively?

Yes. Really, _maybe_allow_interrupt takes as parameter something on which it can call the quit() method whenever ctrl-c is triggered (perhaps the argument should be quit_func -- the bound methods qapp.quit and event_loop.quit, respectively). This can be the full QApplication, in the usual plt.show() case (QApplication runs its own "main" event loop -- see https://doc.qt.io/qt-6/qapplication.html#exec), but can also be an inner event loop (an actual QEventLoop), which manages the context for plt.pause().

Thanks for the clarification. My take on this is:

• we want this context manager to be general puropse: take something that is quittable.
• for QApplication, we need to close the windows in the handler

Thus, the hasattr(qapp, "allWindows") is a valid approach and we should adapt the documentation for the intended inputs on _may_allow_interrupt().

1. I think you can just call closeAllWindows(), which does the loop for you?
2. I'm still a bit confused why in your case, quit() doesn't close all windows -- shouldn't it do so? (I haven't actually tried running anything.)

From the docs https://doc.qt.io/qt-6/qcoreapplication.html#quit it looks like it does not actually close all open windows:

import sys
from PyQt6.QtWidgets import QApplication, QWidget, QLabel, QPushButton


app = QApplication(sys.argv)
widget = QWidget()

textLabel = QLabel(widget)
textLabel.setText("Hello World!")
textLabel.move(110, 85)

widget.setWindowTitle("PyQt6 Example")

button1 = QPushButton(widget)
button1.setText("Button1")
button1.move(64, 32)

def test():
    print("pushed the button!")
    app.quit()
    print("tried to quit!")

button1.clicked.connect(test)


widget.show()


input("hit enter: ")

In the case of making an EventLoop object you likely do not want to close all of the windows when you quit the loop (as they tend to be used as "sub" event loops).

None of this works with PySide because they do not install a input hook.

#26970 is related in spirit

I now use closeAllWindows(). While it may not be the prettiest solution, I think this is a partial and viable improvement.