class Driver(QtCore.QObject):
    update_ui = QtCore.pyqtSignal()
    queue_emptied = QtCore.pyqtSignal()
    initialized = Bool()

    def check_busy(self):
        """
        Handles writing of busy to False.

        Must always write to busy.
        """
        if self.is_busy():
            time.sleep(0.01)  # don't loop like crazy
            self.busy.write(True)
        elif self.enqueued.read():
            time.sleep(0.1)  # don't loop like crazy
            self.busy.write(True)
        else:
            self.busy.write(False)
            self.update_ui.emit()

    @QtCore.pyqtSlot(str, list)
    def dequeue(self, method, inputs):
        """
        Slot to accept enqueued commands from main thread.

        Method passed as qstring, inputs as list of [args, kwargs].

        Calls own method with arguments from inputs.
        """
        self.update_ui.emit()
        method = str(method)  # method passed as qstring
        args, kwargs = inputs
        if g.debug.read():
            print(self.name, ' dequeue:', method, inputs, self.busy.read())
        self.enqueued.pop()
        getattr(self, method)(*args, **kwargs)
        if not self.enqueued.read():
            self.queue_emptied.emit()
            self.check_busy()

    def is_busy(self):
        return False