Python, reference class instance/method in decorated function

Question

I'm having a hard time finding a way to reference class instances in a decorator function.

import json
import time
import sys
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from main_UI import Ui_ApplicationWindow
from slack import RTMClient

class WorkerThread(QThread):
  finished = pyqtSignal(str)   

  def __init__(self):
    QThread.__init__(self)  
    self.rtm_client = RTMClient(token="xoxp...") 

  def run(self):     
    self.rtm_client.start()

  @RTMClient.run_on(event="message")
  def say_hello(**payload):
    data = payload['data']
    if (len(data) != 0):
      if "text" in data:          
        text = data['text']         
        self.finished.emit(str(text))  


class ApplicationWindow(QMainWindow):

  def __init__(self):
    super(ApplicationWindow, self).__init__()
    self.ui = Ui_ApplicationWindow()
    self.ui.setupUi(self)   
    self.ui.pushButton.clicked.connect(self.start_rtm)      

  def start_rtm(self):
    self.thread = WorkerThread()
    self.thread.finished.connect(self.update)
    self.thread.start()

  @pyqtSlot(str)
  def update(self, data):
    self.ui.label.setText(data)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    myWindow = ApplicationWindow()
    myWindow.show()
    app.exec_()

So in say_hello since it can't take self as an argument, I'm not able to use self.finished.emit(text) at the end of the function.

How can I reference a class instance/function using self in say_hello?

Answer 1

No, You can not. Instead of using the @RTMClient.run_on() decorator, use the RTMClient.on() function to register it.

import threading
import asyncio

from slack import RTMClient

from PyQt5 import QtCore, QtWidgets


class SlackClient(QtCore.QObject):
    textChanged = QtCore.pyqtSignal(str)

    def start(self):
        RTMClient.on(event="message", callback=self.say_hello)
        threading.Thread(target=self._start_loop, daemon=True).start()

    def _start_loop(self):
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        slack_token = "xoxb-...."
        rtm_client = RTMClient(token=slack_token)
        rtm_client.start()

    def say_hello(self, **payload):
        data = payload["data"]
        if data:
            if "text" in data:
                text = data["text"]
                self.textChanged.emit(text)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)

    client = SlackClient()

    button = QtWidgets.QPushButton("Start")
    textedit = QtWidgets.QPlainTextEdit()

    button.clicked.connect(client.start)
    client.textChanged.connect(textedit.appendPlainText)

    w = QtWidgets.QWidget()
    lay = QtWidgets.QVBoxLayout(w)
    lay.addWidget(button)
    lay.addWidget(textedit)
    w.show()

    sys.exit(app.exec_())

Update:

import sys
import threading
import asyncio

from slack import RTMClient

from PyQt5 import QtCore, QtWidgets
from main_UI import Ui_ApplicationWindow


class SlackClient(QtCore.QObject):
    textChanged = QtCore.pyqtSignal(str)

    def start(self):
        RTMClient.on(event="message", callback=self.say_hello)
        threading.Thread(target=self._start_loop, daemon=True).start()

    def _start_loop(self):
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        slack_token = "xoxb-...."
        rtm_client = RTMClient(token=slack_token)
        rtm_client.start()

    def say_hello(self, **payload):
        data = payload["data"]
        if data:
            if "text" in data:
                text = data["text"]
                self.textChanged.emit(text)


class ApplicationWindow(QtWidgets.QMainWindow):
    def __init__(self):
        super(ApplicationWindow, self).__init__()
        self.ui = Ui_ApplicationWindow()
        self.ui.setupUi(self)

        self.client = SlackClient()
        # connections
        self.ui.pushButton.clicked.connect(self.client.start)
        self.client.textChanged.connect(self.ui.label.setText)


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    myWindow = ApplicationWindow()
    myWindow.show()
    sys.exit(app.exec_())

Answer 2

Actually you cannot self since that is a global variable, not a class one.

from slack import RTMClient

class WorkerThread(QThread):
    finished = pyqtSignal(dict)

    def __init__(self):
        QThread.__init__(self)
        self.rtm_client = RTMClient(token="xoxp-....")    

    def run(self):
        self.rtm_client.start()

    @RTMClient.run_on(event="message")
    def say_hello(**payload):
        data = payload['data']
        if (len(data) != 0):
            if "text" in data:          
                text = data['text']                      
                WorkerThread.finished.emit(text)  <--- using self impossible 

I suggest that you make such variable private by appending two underscores at the beginning (__my_private_var)