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Asynchronous call from QML to Python with callback


There is no indication from the documentation that QJSValue is thread safe. This page indicates the classes that are re-entrant or thread safe are marked as such in the documentation. However, there is no mention of the word thread on the page for QJSValue.

As such, I would suggest you make sure that your callback is only called from the main thread. Obviously, you are still going to want to put your long running task in a thread, so I would suggest using something like QCoreApplication.postEvent() to send an event from your Python thread to the main thread, which will then call your callback function.

Note: I've wrapped calls to QCoreApplication.postEvent for PyQt4 here. If you need help understanding how to use the QCoreApplication.postEvent method, you can probably adapt it to work with PyQt5 as well.


Categories : Python

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