Import outside toplevel (bad or acceptable?)

by Martin Fitzpatrick Last updated Sep 17 PyQt5 FAQ

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PedanticHacker | 2021-02-15 17:48:01 UTC | #1

Hello! :)

I have a need (since I'm very pedantic) to fix a thing that Pylint is complaining about in my code.

python

superchess.py
Line: 59
pylint: import-outside-toplevel / Import outside toplevel (source.window.main_window) (col 8)

Please look at my code on GitHub HERE and tell me how can I fix that nagging Pylint message.

I've tried everything and I can't have my code working other than importing main_window inside an if block. I read on some forum that having imports like I do indicate a code smell.

All tries other than what I have now give me this error message: QWidget: Must construct a QApplication before a QWidget

Any help or suggestion would be very welcome. Thanks in advance!

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Eolinwen | 2021-02-25 23:05:39 UTC | #2

Hi, We don't have access to your code on Github (error 404)

PedanticHacker | 2021-02-27 01:25:58 UTC | #3

Yeah, sorry about that. The link works now.

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So, what can I do to fix my problem? (The line in question is now 64, not 59.)

martin | 2021-03-05 22:40:33 UTC | #4

The problem is that the import of main_window is creating a QWidget -- you're creating an instance of that window object in that file, which you're then importing -- normally I would import the class, and create the instance of it in this file, e.g.

python

            from source.window import MainWindow  # or whatever it's called
            main_window = MainWindow()
            main_window.show()

That will postpone the creation of the widget til this point, where the QApplication instance exists.

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Import outside toplevel (bad or acceptable?) was written by Martin Fitzpatrick .

Martin Fitzpatrick has been developing Python/Qt apps for 8 years. Building desktop applications to make data-analysis tools more user-friendly, Python was the obvious choice. Starting with Tk, later moving to wxWidgets and finally adopting PyQt. Martin founded PythonGUIs to provide easy to follow GUI programming tutorials to the Python community. He has written a number of popular Python books on the subject.

Import outside toplevel (bad or acceptable?) was published in faq on February 15, 2021 (updated September 17, 2024) . Feedback & Corrections can be submitted here.

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