PyQt 4.6+

PyQt-4.6 and greater have a new API called API2 that is the default when run on Python-3.x. The major difference is that QString does not exist in API2; the library uses the native Python3 str type instead.

One method of porting is to replace all occurrences of QString with ordinary python strings.

If you want code that is the same for Python 2.x and Python 3.x there's a few options to try. You can continue using QString if you use the following code:

try:
    from PyQt4.QtCore import QString
except ImportError:
    # we are using Python3 so QString is not defined                                                                                                                                                                                        
    QString = type("")

You can also set your code to use API2 even when running on python2 and then port all of your code to API2.

import sip
sip.setapi('QString', 2)

from PyQt4 import QtCore

# Now QtCore.QString is no longer available -- use python2's unicode type instead

From the pyqt4 reference manual

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PyQt 4.6+