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How can I use trio in conjunction with PyQT5? The thing is that my program has interface written using PyQT5, and now I need to run eventloop trio, to work with the network, because I use trio WebSocket to connect to the server. I read that I should use trio.lowlevel.start_guest_run for this purpose. But in the documentation it says that in addition to the trio function I must pass run_sync_soon_threadsafe and done_callback as arguments. The documentation gives an example with asyncio and says that I have to define similar functions for my event_loop, in my case for PyQT. Unfortunately my knowledge is not enough to do it myself. I wrote a very simple application using PyQT and put in the body of the class an asynchronous function that if it works correctly should change the inscription on the timer every second. In addition you can enter text in the input box and by pressing the button this text will be displayed at the bottom. I did not run the asynchronous function, as that is my question. At best, I expect the answer to my question to be a modified program in which the asynchronous function and the PyQT5 components run in the same thread using trio. Thank you for your reply.

# -*- coding: utf-8 -*-
 
from PyQt5 import QtCore, QtGui, QtWidgets
import trio
 
class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(804, 595)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.verticalLayoutWidget = QtWidgets.QWidget(self.centralwidget)
        self.verticalLayoutWidget.setGeometry(QtCore.QRect(10, 10, 781, 591))
        self.verticalLayoutWidget.setObjectName("verticalLayoutWidget")
        self.verticalLayout = QtWidgets.QVBoxLayout(self.verticalLayoutWidget)
        self.verticalLayout.setContentsMargins(0, 0, 0, 0)
        self.verticalLayout.setObjectName("verticalLayout")
        spacerItem = QtWidgets.QSpacerItem(20, 40, QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Expanding)
        self.verticalLayout.addItem(spacerItem)
        self.lineEdit = QtWidgets.QLineEdit(self.verticalLayoutWidget)
        font = QtGui.QFont()
        font.setPointSize(20)
        self.lineEdit.setFont(font)
        self.lineEdit.setObjectName("lineEdit")
        self.verticalLayout.addWidget(self.lineEdit)
        self.pushButton = QtWidgets.QPushButton(self.verticalLayoutWidget)
        font = QtGui.QFont()
        font.setPointSize(20)
        self.pushButton.setFont(font)
        self.pushButton.setObjectName("pushButton")
        self.verticalLayout.addWidget(self.pushButton)
        self.label = QtWidgets.QLabel(self.verticalLayoutWidget)
        font = QtGui.QFont()
        font.setPointSize(20)
        self.label.setFont(font)
        self.label.setAlignment(QtCore.Qt.AlignCenter)
        self.label.setObjectName("label")
        self.verticalLayout.addWidget(self.label)
        spacerItem1 = QtWidgets.QSpacerItem(20, 40, QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Expanding)
        self.verticalLayout.addItem(spacerItem1)
        self.label_2 = QtWidgets.QLabel(self.verticalLayoutWidget)
        font = QtGui.QFont()
        font.setPointSize(20)
        self.label_2.setFont(font)
        self.label_2.setAlignment(QtCore.Qt.AlignCenter)
        self.label_2.setObjectName("label_2")
        self.verticalLayout.addWidget(self.label_2)
        spacerItem2 = QtWidgets.QSpacerItem(20, 40, QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Expanding)
        self.verticalLayout.addItem(spacerItem2)
        MainWindow.setCentralWidget(self.centralwidget)
 
        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)
 
    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Pushme"))
        self.label.setText(_translate("MainWindow", ""))
        self.label_2.setText(_translate("MainWindow", "Time"))
 
class PushMe(Ui_MainWindow):
    def __init__(self,  MainWindow):
        super(PushMe, self).__init__()
        self.setupUi(MainWindow)
 
        self.PushMe = MainWindow
 
        self.lineEdit.setPlaceholderText("type something")
 
        self.connect_button()
 
        # self.timer()
 
    def connect_button(self):
        self.pushButton.clicked.connect(self.set_text)
 
    def set_text(self):
        self.label.setText(self.lineEdit.text())
 
    async def timer(self):
        a = 1
        while True:
            self.label_2.setText(str(a))
            a += 1
            await trio.sleep(1)
 
if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = PushMe(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())
Игорь Платонов
  • 11
  • 3

2 Answers2

1

I have to admit that I haven't been keeping up on maintenance on QTrio, but it does mix Qt with Trio. https://qtrio.readthedocs.io/en/stable/ Depending what route you want to go you could either use it as a whole library, or you could just pick out the pieces you want.

https://github.com/altendky/qtrio/blob/43c7ff24c0be2f7a3df86eef3c6cc5dae2f7ffd3/qtrio/_core.py#L649-L657

trio.lowlevel.start_guest_run(
    self.trio_main,
    async_fn,
    args,
    run_sync_soon_threadsafe=self.run_sync_soon_threadsafe,
    done_callback=self.trio_done,
    clock=self.clock,  # type: ignore[arg-type]
    instruments=self.instruments,
)

https://github.com/altendky/qtrio/blob/43c7ff24c0be2f7a3df86eef3c6cc5dae2f7ffd3/qtrio/_core.py#L672-L683

def run_sync_soon_threadsafe(self, fn: typing.Callable[[], object]) -> None:
    """Helper for the Trio guest to execute a sync function in the Qt host
    thread when called from the Trio guest thread.  This call will not block waiting
    for completion of ``fn`` nor will it return the result of calling ``fn``.
    Args:
        fn: A no parameter callable.
    """
    import qtrio.qt

    event = qtrio.qt.ReenterEvent(fn=fn)
    self.application.postEvent(self.reenter, event)
altendky
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  • I read the qtrio documentation from start to finish, but it is written in a way that makes me feel like I have to completely rewrite my (existing) application so that it works using this package. I may be wrong, but my knowledge of an inexperienced user learning Python on YouTube was only enough to reach such conclusions. – Игорь Платонов Sep 07 '22 at 12:46
  • I just experimented and most likely found a way to run already written applications, with minimal changes to the code. Maybe you as an experienced user will find some obvious mistakes in my approach and I would like you to point them out. If you don't find anything critical, in that case, I will use this code as an answer to my question. Thank you. https://pastebin.com/w96DmVu5 – Игорь Платонов Sep 07 '22 at 12:47
  • There are a few layers to QTrio. To start, you may only want the base layer and you found that. Maybe I can find some time to review the documentation to be more explicit about that. The 'higher layers' are indeed an exploration of a completely different approach to writing GUI applications. Just as Trio's structured concurrency encourages a different design than asyncio or Twisted. – altendky Sep 07 '22 at 14:29
0

Most likely the easiest way is to use qtrio.Runner. Below I have run an asynchronous function using this class by adding just 2 lines of code to an already completed application. In my case this is the answer to my question.

# -*- coding: utf-8 -*-
import qtrio
from PyQt5 import QtCore, QtGui, QtWidgets
import trio
 
class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(804, 595)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.verticalLayoutWidget = QtWidgets.QWidget(self.centralwidget)
        self.verticalLayoutWidget.setGeometry(QtCore.QRect(10, 10, 781, 591))
        self.verticalLayoutWidget.setObjectName("verticalLayoutWidget")
        self.verticalLayout = QtWidgets.QVBoxLayout(self.verticalLayoutWidget)
        self.verticalLayout.setContentsMargins(0, 0, 0, 0)
        self.verticalLayout.setObjectName("verticalLayout")
        spacerItem = QtWidgets.QSpacerItem(20, 40, QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Expanding)
        self.verticalLayout.addItem(spacerItem)
        self.lineEdit = QtWidgets.QLineEdit(self.verticalLayoutWidget)
        font = QtGui.QFont()
        font.setPointSize(20)
        self.lineEdit.setFont(font)
        self.lineEdit.setObjectName("lineEdit")
        self.verticalLayout.addWidget(self.lineEdit)
        self.pushButton = QtWidgets.QPushButton(self.verticalLayoutWidget)
        font = QtGui.QFont()
        font.setPointSize(20)
        self.pushButton.setFont(font)
        self.pushButton.setObjectName("pushButton")
        self.verticalLayout.addWidget(self.pushButton)
        self.label = QtWidgets.QLabel(self.verticalLayoutWidget)
        font = QtGui.QFont()
        font.setPointSize(20)
        self.label.setFont(font)
        self.label.setAlignment(QtCore.Qt.AlignCenter)
        self.label.setObjectName("label")
        self.verticalLayout.addWidget(self.label)
        spacerItem1 = QtWidgets.QSpacerItem(20, 40, QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Expanding)
        self.verticalLayout.addItem(spacerItem1)
        self.label_2 = QtWidgets.QLabel(self.verticalLayoutWidget)
        font = QtGui.QFont()
        font.setPointSize(20)
        self.label_2.setFont(font)
        self.label_2.setAlignment(QtCore.Qt.AlignCenter)
        self.label_2.setObjectName("label_2")
        self.verticalLayout.addWidget(self.label_2)
        spacerItem2 = QtWidgets.QSpacerItem(20, 40, QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Expanding)
        self.verticalLayout.addItem(spacerItem2)
        MainWindow.setCentralWidget(self.centralwidget)
 
        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)
 
    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Pushme"))
        self.label.setText(_translate("MainWindow", ""))
        self.label_2.setText(_translate("MainWindow", "Time"))
 
class PushMe(Ui_MainWindow):
    def __init__(self,  MainWindow):
        super(PushMe, self).__init__()
        self.setupUi(MainWindow)
 
        self.PushMe = MainWindow
 
        self.lineEdit.setPlaceholderText("type something")
 
        self.connect_button()
 
        # self.timer()
 
    def connect_button(self):
        self.pushButton.clicked.connect(self.set_text)
 
    def set_text(self):
        self.label.setText(self.lineEdit.text())
 
    async def timer(self):
        a = 1
        while True:
            self.label_2.setText(str(a))
            a += 1
            await trio.sleep(1)
 
 
if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = PushMe(MainWindow)
    MainWindow.show()
    trio_loop = qtrio.Runner(application=app)
    trio_loop.run(ui.timer)
    sys.exit(app.exec_())
Игорь Платонов
  • 11
  • 3