How to access variables and methods from QMainWindow Class in a QWidget Class

I'm building a media player with PyQt5 in python and I want to access variables from my QMainWindow class. Currently I have two classes - one is the main window (QMainWindow) and the other is a QWidget Window so called my export manager.

Some basic code of my structure

class MainWindow(QMainWindow):

    def __init__(self, parent=None):
        super().__init__(parent)
        
        # create gui
        # some basic functions


    # A function for opening a video with selection of file in explorer

    def OpenVideo1(self, filename1=None):

        file_filter = 'Video file (*.mp4 *.avi *wmv);'

        filename1 = QFileDialog.getOpenFileName(
            parent = self,
            caption='Select a video file',
            directory = os.getcwd(),
            filter = file_filter,
            initialFilter='Video file (*.mp4 *.avi *wmv)'
        )[0]

        ....

    # On button click the export manager window opens

    def OpenExportManager(self, checked):
        self.Exp = ExportManager()
        self.Exp.show()

class ExportManager(QWidget):

    def __init__(self, parent=None):
        super().__init__(parent)

    # Some gui functions etc...

    def exportvideo
       # Here I want to excecute some commands for export one video
       # Therefore I need variables from the MainWindow - in this case filename1 and others

if __name__ == "__main__":
    app = QApplication(sys.argv)
    Main = MainWindow()
    Main.show()

My question is now: How can I access the MainWindow variable filename1 from my ExportManager class? And how can I access methods the same way?

I tried already with signal/slots from pyqt5 or some class instances but I'm stuck...

Thanks very much for your help!

PyQt5 signals and slots but I got stuck.

CodePudding user response：

It's a point about Object-Oriented Programming more than about GUI.

You could keep track of the filename1 variable by making it a member of the MainWindow class.

In MainWindow.init() you could add :

    self.chosen_filename: str = None

Then you assign it at the end of the MainWindow.OpenVideo() method

    self.chosen_filename = filename1

When you instantiate the ExportManager object, you can pass the filename as a constructor argument.

def __init__(self, parent=None, filename=None)
    ...