signal_without_qobject.py

from PyQt4 import Qt


class Signaller(Qt.QObject):
    signal = Qt.pyqtSignal()


class Base(object):
    """Base is not a QObject but provides a pyqtSignal signal member via
    a Signaller hidden behind a property"""
    def __init__(self):
        self._signaller = Signaller()

    @property
    def signal(self):
        return self._signaller.signal


class MyWidget(Qt.QLabel, Base):
    """3rd party widget which expects "signal" to be provided by Base"""
    def __init__(self):
        Qt.QLabel.__init__(self, 'testing signal')
        Base.__init__(self)

        # self.signal can now be used as expected
        self.signal.connect(self.onSignal)
        self.signal.emit()

    def onSignal(self):
        print "got signal!!!"

app=Qt.QApplication([])
w = MyWidget()

w.show()

app.exec_()