pyside - Is there a way of getting log information for every event in the event loop?

Question

I'm developing an application with PySide, and I was wondering if there is a way of logging which events enter the main event loop and which ones leave. my application use no threads, it is complete asynchronous, but I wanted to have log registries of the event loop for debugging purpose. I use logging as my logging facility (duh).

Pax et bonum.

Answer 1

As a good user on reddit replies:

Check this out: http://qt-project.org/doc/qt-4.8/qcoreapplication.html#notify. The event loop is implemented in QCoreApplication, so you can subclass and install your own code to inspect events.

class Application(QApplication): events = {constant: name for name,constant in QEvent.dict.items() if name[0].isupper() and isinstance(constant, int)}

def notify(self, obj, event):
    print("{:<20}{}".format(Application.events[event.type()], obj))
    return super().notify(obj, event)

Works pretty well. http://i.imgur.com/mMLqQ5Y.png

Of course, you will still have to work out which events are being consumed. That super call returns True or False, but almost every event I saw was returning True. Your might have to traverse object relationships or something—I'm not sure because I haven't done this, but there appears to be pretty good support for getting down into that loop and doing what you like.

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However, I'm more inclined to follow the third option listed on Qt's documentation:

3. Installing an event filter on QCoreApplication::instance(). Such an event filter is able to process all events for all widgets, so it's just as powerful as reimplementing notify(); furthermore, it's possible to have more than one application-global event filter. Global event filters even see mouse events for disabled widgets. Note that application event filters are only called for objects that live in the main thread.