从GUI类外部访问GUI元素

Question

I'm hoping someone can help me with a Qt designer question. I'm trying to modify GUI elements from outside the class calling the GUI file. I've set up example code showing the structure of my programs. My goal is to get func2 , in the main program (or another class) to change the main window's statusbar.

from PyQt4 import QtCore, QtGui
from main_gui import Ui_Main
from about_gui import Ui_About
#main_gui and about_gui are .py files generated by designer and pyuic

class StartQT4(QtGui.QMainWindow):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)
        self.ui = Ui_Main()
        self.ui.setupUi(self)

        self.ui.actionMyaction.triggered.connect(self.func1)
    #Signals go here, and call this class's methods, which call other methods.
        #I can't seem to call other methods/functions directly, and these won't take arguments.

    def func1(self):
    #Referenced by the above code. Can interact with other classes/functions.
        self.ui.statusbar.showMessage("This works!")


def func2(self):
   StartQT4.ui.statusbar.showMessage("This doesn't work!")
    #I've tried many variations of the above line, with no luck.

#More classes and functions not directly-related to the GUI go here; ie the most of the program.

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    myapp = StartQT4()
    myapp.show()
    sys.exit(app.exec_())

I'm trying to get func2 to work, since I don't want my whole program to be under the StartQT4 class. I've tried many variations of that line, but can't seem to access GUI items from outside of this class. I've tried sending signals as well, but still can't get the syntax right.

It's possible that my structure is bogus, which is why I posted most of it. Essentially I have a .py file created by Designer, and my main program file, which imports it. The main program file has a class to initiate the GUI, (and a class for each separate window). It has signals in this class, that call methods in the class. These methods call functions from my main program, or other classes I've created. The end of the program has the if __name__ == "__main__" code, to start the GUI. Is this structure bogus? I've read many tutorials online, all different, or outdated.

Answer 1

Your func1 method is a way to go - since ui is a field in StartQT4 class, you should directly manipulate with its data only within the same class. There is nothing wrong that you have all user interface functionality for one widget in one class - it is not a big issue if you have only two classes in your code, but having several classes to reference the fields directly is potential nightmare for maintentace (what if you change the name of statusbar widget?).

However, if you actually want to edit it from func2 , then you need to pass the reference of StartQT4 object to it, because you need to specify for what instance of window you need to change status bar message.

def func2(qtWnd): # Self should go here if func2 is beloning to some class, if not, then it is not necessary
   qtWnd.ui.statusbar.showMessage("This should work now!")

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    myapp = StartQT4()
    myapp.show()
    func2(myapp)
    sys.exit(app.exec_())