PyQt5: How to move a QObject to the main thread?

Question

I know that in general, QObject() instances should be created in the main thread. I also know that - once created - you can move a QObject() from the main thread to another one:

official Qt docs can be found here

    # Worker-object approach
    # -----------------------
    # Note: these codelines execute in the main thread.
    workerThread = QThread()
    workerObj = WorkerObj()
    workerObj.moveToThread(workerThread)

 
Currently I am facing the exact opposite problem. I have a QObject() instantiated in a (non-main) QThread. I want to move it to the main thread, like this:

    # Move a QObject() to the main thread
    # ------------------------------------
    # Note: these codelines execute in some QThread
    myObj = QObject()
    myObj.moveToThread(threading.main_thread())

I get the following error:

TypeError: moveToThread(self, QThread): argument 1 has unexpected type '_MainThread'

I probably get the error because the main thread is not a genuine QThread. What should I do to make it work?

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EDIT:
Apparently the answer was right in the documentation of the moveToThread() function. This is pretty embarrassing. My sincere apologies. I'll be more careful next time.

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Answer 1

QObject instances can be created in any thread, of course. And they are, and Qt would be quite useless without it. What you're looking for is the global application object - and its thread:

myObj = QObject()
mainThread = QCoreApplication.instance().thread()
myObj.moveToThread(mainThread)

It is undefined behavior to call, from the current thread, any non-thread-safe methods on the object after the moveToThread call. Past this call, the object's non-thread-safe methods can be safely used from the target thread only.