PyQt4: slots and signals. How to pass a signal from Scrapy to PyQt?

Question

Python

Already asked a question, but ... and did not solve anything. I figured out the signals and slots, but I can’t transfer the information like that. Perhaps because of a different flow (which should not be an obstacle for signals), or perhaps because of crooked hands. I had the following code:

# -*- coding: utf-8 -*-
from PyQt4 import QtCore, QtGui

class SignalClass(QtCore.QObject):
    signal = QtCore.pyqtSignal(object)

    def __init__(self):
        QtCore.QObject.__init__(self)

    def send(self, text):
        self.signal.emit(text)

# Часть, которая будет выводить текст
@QtCore.pyqtSlot(object)
def output(text):
    print text

# Часть, которая будет передавать текст
bag = SignalClass()
bag.signal.connect(output)
bag.send(2) # Тут передаем значение функции output

That's how everything works. I distribute everything according to PyQt and Scrapy - nothing is transferred to QLabel. Any ideas?

Answer 1

If you have pyqt4 and twisted (used in scrapy) reactors (event loops) running in the same process (but, for example, in different threads), then these reactors will not release the GIL => the application will not work or will work in an unexpected way. There should not be more than one reactor in one Python process.
stackoverflow.com/questions/15087746/qt4reactor-sc...