show() and exec_() behavior difference

[Junhi]

Hello.
I have spent many time for solving the problem.

I made code that display QDialog window when a condition meet.

Here is part of code

    def display_message(self):
        global result_display

        self.Dialog = QtWidgets.QDialog()
        self.dm = Warning_Window(result_display)
        self.dm.setupUi(self.Dialog)
        self.Dialog.exec_()

When I use self.Dialog.exec_(), QDialog window displays
but in case of self.Dialog.show(), my program does not response

Below is code
main.py

class Form(QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super().__init__()
        self.setupUi(self)
        self.show()

    @pyqtSlot()
    def display_message(self):
        global result_display

        self.Dialog = QtWidgets.QDialog()
        self.dm = Warning_Window(result_display)
        self.dm.setupUi(self.Dialog)
        self.Dialog.exec_()


    def discover_sleeping_cell(self):

        global order
        global result_display


            if (len(result_display) != 0):

                p1 = Thread(target=self.display_message)
                p1.start()


        cursor.close()
        conn.close()
        fp_sleeping_cell.close()

        order = order + 1
        if order > 32:
            pass
        else :
            self.wait_10min()


    def wait_10min(self):
        global order

        t = threading.Timer(1.0,self.discover_sleeping_cell)
        t.start()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    global w
    w = Form()

    file_list = []
    order = 0
    w.wait_10min()

    sys.exit(app.exec_())

warning_window.py

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'C:\Users\think\Documents\monitor\warning_window.ui'
#
# Created by: PyQt5 UI code generator 5.13.0
#
# WARNING! All changes made in this file will be lost!


from PyQt5 import QtCore, QtGui, QtWidgets


class Warning_Window(object):

    def __init__(self,msg):
        global list_of_sleeping_cell

        list_of_sleeping_cell = msg
        if list_of_sleeping_cell == 'none':
            pass
        print(list_of_sleeping_cell)

    def setupUi(self, dialog):

        dialog.setObjectName("Dialog")
        dialog.resize(500, 400)
        self.horizontalLayout = QtWidgets.QHBoxLayout(dialog)
        self.horizontalLayout.setObjectName("horizontalLayout")

        self.warn_sleeping = QtWidgets.QTextBrowser(dialog)

        self.warn_sleeping.setFrameShape(QtWidgets.QFrame.StyledPanel)
        self.warn_sleeping.setFrameShadow(QtWidgets.QFrame.Plain)
        self.warn_sleeping.setLineWidth(3)
        self.warn_sleeping.setMidLineWidth(1)

        self.warn_sleeping.setAlignment(QtCore.Qt.AlignLeading|QtCore.Qt.AlignLeft|QtCore.Qt.AlignTop)
        self.warn_sleeping.setObjectName("warn_sleeping")
        self.horizontalLayout.addWidget(self.warn_sleeping)

        self.retranslateUi(dialog)
        QtCore.QMetaObject.connectSlotsByName(dialog)

        ################################################
        lenth_sleeping_cell_list = len(list_of_sleeping_cell)

        self.warn_sleeping.setText("Message")


        ################################################

    def retranslateUi(self, dialog):
        _translate = QtCore.QCoreApplication.translate
        dialog.setWindowTitle(_translate("Dialog", "Dialog"))
        self.warn_sleeping.setText(_translate("Dialog", "TextLabel"))


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    Dialog = QtWidgets.QDialog()
    ui = Warning_Window()
    ui.setupUi(Dialog)
    Dialog.show()
    sys.exit(app.exec_())

[JonB]

@Junhi said in show() and exec_() behavior difference:

but in case of self.Dialog.show(), my program does not response

Don't know what that means.

show() and exec() work as documented, whether in C++ or Python.

p1 = Thread(target=self.display_message): what are you doing trying to use threads here, especially with Python? Further, you are trying to make the thread execute a Qt UI behaviour, which is absolutely forbidden in Qt (UI stuff can only be executed in the main GUI thread), and could easily be your issue.

Why does your warning_window.py have all the if __name__ == "__main__": code, it's just confusing?

So start by sorting out your code, in particular remove any thread stuff, and see where you are then.

[Junhi]

@JonB Thank you for your feedback

1. "but in case of self.Dialog.show(), my program does not response" means
   When I use self.Dialog.exec_() at 5th line in the display_message() method,
   I can see QDialog window pop-up.
   But when I use self.Dialog.show() instead of self.Dialog.exec_(), QDialog window does not pop-up and main program got hang(no response).

2. p1 = Thread(target=self.display_message): could easily be your issue.
   I have changed the code like below, but same result

           if (len(result_display) != 0):

#                p1 = Thread(target=self.display_message)
#                p1.start()
                self.display_message()

3. ave all the if name == "main": code, it's just confusing?
   Yes, it is just confusing. This is my first GUI code.
   So difficult than non GUI programming. -_-;;
   What is your recommendation?

[jsulm]

@Junhi Why do you have

if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    Dialog = QtWidgets.QDialog()
    ui = Warning_Window()
    ui.setupUi(Dialog)
    Dialog.show()
    sys.exit(app.exec_())

in warning_window.py ?

[Junhi]

@jsulm Hmmm.. I don't know why.
Cause warning_window.py is from QT Designer.
I just design by using QT Design and convert .ui to .py

[Junhi]

@Junhi said in show() and exec_() behavior difference:

@jsulm Hmmm.. I don't know why.
Cause warning_window.py is from QT Designer.
I just design by using QT Design and convert .ui to .py

I had just removed main and had test again. but Same result

#if __name__ == "__main__":
#    import sys

#    app = QtWidgets.QApplication(sys.argv)
#    Dialog = QtWidgets.QDialog()
#    ui = Warning_Window()
#    ui.setupUi(Dialog)
#    Dialog.show()
#    sys.exit(app.exec_())

[RokeJulianLockhart]

@Junhi,

if __name__ == "__main__":

prevents invocation as module, instead only as script.