Python: Execute callback method in main thread

Question

Not wanting my GUI to freeze, I've decided to use a thread for a file operation. Currently I'm using thread.start_new_thread(self.openFile, (filepath, self.openedFile)) to do so, with self.openedFile being my callback method. Inside self.openFile it is just invoked using callback(success).

But unfortunately I couldn't figure out how to execute my callback in the main thread instead of the newly created one. This is required as the GUI cannot be modified from another thread.

I really appreciate all your help!

Community · Accepted Answer · 2017-05-23 12:33:21Z

4

The thread owning the GUI will have to periodically check a Queue.Queue instance on which other threads can put work requests (e.g a callback function and arguments for it).

How easy or hard it is to insert such checks within a GUI's main loop is 100% dependent on exactly what GUI framework you're using.

For example if you're using Tkinter, the after method of widgets lets you do such periodic checks, as explained e.g at Run an infinite loop in the backgroung in Tkinter .

edited May 23, 2017 at 12:33

CommunityBot

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answered Jan 31, 2015 at 17:14

Alex Martelli

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2 Comments

stoeffn Over a year ago

Thanks! Do you know the PyQT equivalent to Tkinter's after? I couldn't find it in the documentation.

Alex Martelli Over a year ago

I believe QTimer is what you'd use, srinikom.github.io/pyside-docs/PySide/QtCore/QTimer.html .

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