multiple classes in PyQt4

Question

After learning the Python basics I'm now trying myself in GUI using PyQt4. Unfortunately I'm now stuck figuring out how to use multiple classes and after spending a lot of time trying to get the answer online and not really finding the right answer I hope you can now help me.

So this is my example code:

import sys
from PyQt4 import QtGui, QtCore

class Example(QtGui.QWidget):

    def __init__(self):
        super(Example, self).__init__()

        self.initUI()

    def initUI(self):

        self.b1 = QtGui.QPushButton("Button", self)
        self.b1.move(100,100)


        self.setGeometry(300,300,200,200)
        self.setWindowTitle("Example")
        self.show()

class Bar(QtGui.QMainWindow):

    def __init__(self):
        QtGui.QMainWindow.__init__(self)

        self.initUI()

    def initUI(self):

        self.statusBar().showMessage("Statusbar")


def main():
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec())

if __name__ == "__main__":
    main()

Right now only the Button from the "Example" class shows up but not the statusBar from the "Bar" class. So how exactly can I use both classes simultaneously? Does one have to inherit something from the other? Sorry if this might be very clumsy and have a lot of mistakes but thanks if you can help me!

Answer 1

A QMainWindow has QWidgets and one QStatusBar, a QWidget has no QStatusBar. You need to fix your inheritance tree.

import sys
from PyQt4 import QtCore, QtGui

class Example(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(Example, self).__init__(parent)
        self.statusBar().showMessage("howdy stackoverflowers!!")

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

Answer 2

You need to instantiate a Bar object, and call its show method:

def main():
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    bar = Bar()
    bar.show()
    sys.exit(app.exec_())

---

If you want the button and status bar in one window, put all the widgets in the QMainWindow:

import sys
from PyQt4 import QtGui, QtCore

class Bar(QtGui.QMainWindow):

    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        self.initUI()

    def initUI(self):
        self.setGeometry(300,300,200,200)
        self.b1 = QtGui.QPushButton("Button", self)
        self.b1.move(100,100)
        self.setWindowTitle("Example")
        self.statusBar().showMessage("Statusbar")

def main():
    app = QtGui.QApplication(sys.argv)
    bar = Bar()
    bar.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()