qtchat.py

from asyncqt import QEventLoop, asyncSlot, asyncClose
import sys
import asyncio

from PySide2.QtWidgets import (
    QApplication, QWidget, QLabel, QLineEdit, QTextEdit, QPushButton,
    QVBoxLayout)
    
from PySide2.QtCore import Signal


class ClientProtocol(asyncio.Protocol):
    def __init__(self, chat):
        self.window = chat

    def data_received(self, data: bytes):
        decoded = data.decode()
        self.window.speak.emit(decoded)

    def connection_made(self, transport):
        self.transport = transport

    def connection_lost(self, exception):
        pass


class MainWindow(QWidget):

    speak = Signal(str)

    __transport = None
    __protocol = None

    def __init__(self):
        super().__init__()
        self.setLayout(QVBoxLayout())  

        self.editResponse = QTextEdit('', self)
        self.layout().addWidget(self.editResponse)
        
        self.editSend = QLineEdit('', self)
        self.layout().addWidget(self.editSend)
        self.editSend.returnPressed.connect(self.on_editSend)

        self.speak.connect(self.editResponse.append)
        

    @asyncSlot()
    async def on_editSend(self):
        text = self.editSend.text()
        if self.__transport:
            self.__transport.write(text.encode())
            self.editSend.setText('')
            self.editResponse.append('>'+text)

    def set_transport(self, task):
        self.__transport, self.__protocol = task.result()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    loop = QEventLoop(app)
    asyncio.set_event_loop(loop)
    mainWindow = MainWindow()
    
    coro = loop.create_connection(
               lambda : ClientProtocol(mainWindow),
               "127.0.0.1",
               8888
        )
    task = loop.create_task(coro)
    
    task.add_done_callback(mainWindow.set_transport)

    mainWindow.show()

    with loop:
        sys.exit(loop.run_forever())