[FIXED] Using custom object (PyQt_PyObject like) in signal/slots

Issue

I manage to use PySide instead of PyQt because of licensing.

I need to pass custom objets between threads using the signal/slots mechanism. With PyQt, I can use the PyQt_PyObject type as signal argument but obviously, this type doesn't exists in PySide :

TypeError: Unknown type used to call meta function (that may be a signal): PyQt_PyObject

I tried to use object instead of PyQt_PyObject but things happen only with a DirectConnection type between signal and slot :

self.connect(dummyEmitter,
             QtCore.SIGNAL("logMsgPlain(object)"),
             self._logMsgPlain,
             QtCore.Qt.DirectConnection)

With a QueuedConnection, I get an error :

QObject::connect: Cannot queue arguments of type 'object'
(Make sure 'object' is registered using qRegisterMetaType().)

I say "things happen" because it doesn't work so far. I now get errors due to the DirectConnection type :

QObject::startTimer: timers cannot be started from another thread
QPixmap: It is not safe to use pixmaps outside the GUI thread
etc ...

How should I do ? Is there a PyQt_PyObject type-like in PySide ?

EDIT: This small exemple will fail :

from PySide import QtCore, QtGui
import sys

class Object(QtCore.QObject):
    ''' A dummy emitter that send a list to the thread '''
    def emitSignal(self):
        someList = [0, 1, 2, 3]
        self.emit(QtCore.SIGNAL("aSignal(object)"), someList)

class Worker(QtCore.QObject):
    def aSlot(self, value):
        print "List: {}".format(value)

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)

    worker = Worker()
    obj = Object()

    thread = QtCore.QThread()
    worker.moveToThread(thread)
    QtCore.QObject.connect(obj, QtCore.SIGNAL("aSignal(object)"), worker.aSlot)
    # The exemple will pass with the line below uncommented
    # But obviously, I can't use a DirectConnection with a worker thread and the GUI thread
    # QtCore.QObject.connect(obj, QtCore.SIGNAL("aSignal(object)"), worker.aSlot, QtCore.Qt.DirectConnection)

    thread.start()
    obj.emitSignal()

    app.exec_()

Solution

For now, the only solution I found is to switch to new style signal/slot syntax :

from PySide import QtCore, QtGui
import sys

class Object(QtCore.QObject):
    aSignal = QtCore.Signal(object)
    def emitSignal(self):
        someList = [0, 1, 2, 3]
        self.aSignal.emit(someList)

class Worker(QtCore.QObject):
    def aSlot(self, value):
        print "List: {}".format(value)

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)

    worker = Worker()
    obj = Object()

    thread = QtCore.QThread()
    worker.moveToThread(thread)
    obj.aSignal.connect(worker.aSlot)

    thread.start()
    obj.emitSignal()

    app.exec_()

But I would be interested to know if there is a solution with the old-style syntax but for now, it seems that there is not.

Answered By - Loïc G.