[PyQt] Python 3 import error

[Phil Thompson]

On Thu, 2 Dec 2010 13:17:22 +0100, Thorsten Kampe
<thorsten at thorstenkampe.de> wrote:
> * Hans-Peter Jansen (Thu, 2 Dec 2010 12:49:17 +0100)
>> On Thursday 02 December 2010, 12:24:54 Thorsten Kampe wrote:
>> > I'm trying to port a PyQt4 application from Python 2 to Python 3.
>> > The application works fine with the latest Python 2 (2.7.1) but not
>> > with Python 3.1.2:
>> >
>> > Traceback (most recent call last):
>> >   File "my_application.pyw", line 10, in <module>
>> >     import resource.ui
>> >   File "F:\[path]\resource\ui.py", line 84, in <module>
>> >     import resource_rc
>> > ImportError: No module named resource_rc
>> >
>> > This is the directory structure:
>> > |-- my_application.pyw*  (main application, "import resource.ui")
>> >
>> > `-- resource/
>> >
>> >     |-- __init__.py      (package file to enable module import)
>> >     |-- resource_rc.py   (generated by pyrcc4)
>> >
>> >     `-- ui.py            (generated by pyuic4, "import resource_rc")
>> >
>> > I couldn't find any documentation regarding changes between the
>> > latest Python 2 and 3. Who knows what's going on and what I can do?!
>> 
>> Did you recreated the resources with pyrcc4 -py3? It might be necessary

>> to supply a --from-imports argument to pyuic4, as python3 did changed 
>> its import behavior (relative imports, etc..).
> 
> Okay, this is what I get after adding "--from-imports":
> 
> Traceback (most recent call last):
>   File "my_application.pyw", line 10, in <module>
>     import resource.ui
>   File "F:\[path]\resource\ui.py", line 89, in <module>
>     from . import resource_rc
>   File "F:\[path]\resource\resource_rc.py", line 70627,
> in <module>
>     qInitResources()
>   File "F:\[path]\resource\resource_rc.py", line 70622,
> in qInitResources
>     QtCore.qRegisterResourceData(0x01, qt_resource_struct, 
> qt_resource_name, qt_resource_data)
> TypeError: qRegisterResourceData(int, str, str, str): argument 2 has 
> unexpected type 'str'
> 
> 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.

> (...taken from Mark Summerfield's book "Rapid GUI Programming with 
> Python and Qt: The Definitive Guide to PyQt Programming").
> 
> Interestingly the same UI and resource file still run fine in Python 2 
> :-/

.ui files are identical for all versions of Python.

-py3 resource files will work with Python v2.6 and later.

Phil