[PyQt] Python 3 import error

Thorsten Kampe thorsten at thorstenkampe.de
Thu Dec 2 13:25:21 GMT 2010

* Phil Thompson (Thu, 02 Dec 2010 12:39:58 +0000)
> On Thu, 2 Dec 2010 13:17:22 +0100, Thorsten Kampe
> <thorsten at thorstenkampe.de> wrote:
> > So the ImportError is gone. Adding -py3 to pyrcc4 yields:
> > Traceback (most recent call last):
> >   File "my_application.pyw", line 63, in <module>
> >     mainWin       = MainWindow()
> >   File "my_application.pyw", line 19, in __init__
> >     self.restoreGeometry(settings.value('Geometry').toByteArray())
> > AttributeError: 'QByteArray' object has no attribute 'toByteArray'
> > 
> > So the error is now in the main file. The actual line is
> > 
> >     self.restoreGeometry(settings.value('Geometry').toByteArray())
> ...because the QVariant v2 API is the default with Python v3 so it has
> already converted the QVariant to a QByteArray for you.

Okay, if I omit the ".toByteArray()", then the application starts with 
Python 3 - but it doesn't work with Python 2 anymore:

TypeError: QWidget.restoreGeometry(QByteArray): argument 1 has 
unexpected type 'QVariant'

Is there a way around that or do I simply have to query the Python 
version inside the script? Or put in a try "without toByteArray()" if 
exception, try with "toByteArray()"?!

The - hopefully - last problem with the porting to Python 3:
Everything seems to work fine, except closing the application through 
the menu or toolbar (Alt+F4 works fine):

Traceback (most recent call last):
  File "my_application-new.pyw", line 32, in on_actionE_xit_triggered
    settings.setValue('Geometry', QtCore.QVariant(self.saveGeometry()))
TypeError: PyQt4.QtCore.QVariant represents a mapped type and cannot be 

this refers to 
def on_actionE_xit_triggered(self):
    settings = QtCore.QSettings()
    settings.setValue('Geometry', QtCore.QVariant(self.saveGeometry()))

...in the code.


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