Signal-Slot

class Gui(QtCore.QObject, object):  # This is class A that is instanced elsewhere
    capture = cv2.cv.CaptureFromCAM(-1) # Capturing webcam image
    mySignal = QtCore.SIGNAL('mySignal(str)')

    def __init__(self, name=None, parent_node=None, **kwd):
    QtCore.QObject.__init__(self)

    def init_handler(self,  **kwd):  # The initial declarations go here
    self.gui=guiThread(self)
    self.gui.start()

    def compute_handler(self):   # This is the loop that will keep executing periodically
        window = self.gui.window      # This window is the gui created in QtDesigner
    self.tempimage = cv2.cv.QueryFrame(self.capture)
    print "about to emit"
    self.emit(QtCore.SIGNAL('mySignal'),"Hello World")
        print "emitted"

class guiThread(Thread, QtCore.QObject, object):

    def __init__ (self, creator):
    QtCore.QObject.__init__(self)
    self._creator = creator  # And now self._creator is the creator object
        Thread.__init__(self)
        self.app = None
    self.window = None

    def run(self):
    self.app = QtGui.QApplication(sys.argv)
        self.window = MainWindow()
        self.window.show()
    print "about to connect"
    self.connect(self._creator, QtCore.SIGNAL('mySignal'),self.printSuccess)
    print "passed the connect"
    self.app.exec_()

    def printSuccess(self, var):
    print "received", var

    def stop(self):
        self.window.close()


______________ OUTPUT ______________
about to connect
passed the connect
about to emit
emitted
about to emit
emitted
about to emit
emitted
about to emit
emitted
about to emit
emitted
.....