Unable to open a new window from a method

Question

I am developing a simple PyQt5 application and I am trying to open a new window from a parent window with the following function:

def park(self, N):
    from time_dialog import T_MainWindow
    ui = T_MainWindow(self, N)
    ui.show()

And the class I am trying to access is:

class T_MainWindow(QtWidgets.QWidget):
    def __init__(self, parent, N):
        super().__init__()
        self.PARENT = parent
        self.N = N
        self.setupUi()

Both these windows open up if run individually using:

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    ui = T_MainWindow("", "")
    ui.show()
    sys.exit(app.exec_())

Answer 1

When you open the T_MainWindow in the second example, the ui variable is global, so it does not get garbage-collected. But when you open it from the park method, the ui variable is local, so it will be garbage-collected when the method returns (and thus before the window is shown). To fix that, you can change the local variable to an attribute, so that a reference is kept for the window:

def park(self, N):
    from time_dialog import T_MainWindow
    self.t_window = T_MainWindow(self, N)
    self.t_window.show()