Change text when button is clicked - qt

Question

I want to change the text on a button ( Start optimization ) to ( Cancel optimization ) when the text was clicked. So far I got:
class MainWindow(QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
layout = QGridLayout()
layout.addLayout(self.optimize_button(), 1, 3, 1, 1)
widget = QWidget()
widget.setLayout(layout)
self.setCentralWidget(widget)
# method for widgets
def optimize_button(self):
hbox = QHBoxLayout()
button = QPushButton("", self)
button.setText("Start optimization")
button.setGeometry(200, 150, 100, 30)
button.clicked.connect(self.clickme)
#self.push.clicked.connect(self.clickme)
hbox.addWidget(button)
self.show()
return hbox
def clickme(self):
print("pressed")
self.button.setText("Cancel optimization")
I tried to make use out of https://www.geeksforgeeks.org/pyqt5-how-to-change-the-text-of-existing-push-button/ but it doesn't work.
I guess the issue lays somewhere that clicking the button is calling clickme() which doesn't know anything about that button. But I don't know how to refer accordingly.
edit:
def clickme(self):
print("pressed")
self.button = QPushButton("", self)
self.button.setText("Cancel optimization")
is not working?

Answer 1

Option 1: Store it as a class member
A solution is to:
Store the button as a class member during construction
Change the button that is stored as class member.
So, your simplified example would become:
class MainWindow(QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
hbox = QHBoxLayout()
self.button = QPushButton("", self) // (1) store the button as a class member
button.setText("Start optimization")
button.clicked.connect(self.clickme)
hbox.addWidget(button)
widget = QWidget()
widget.setLayout(hbox)
self.setCentralWidget(widget)
self.show()
def clickme(self):
print("pressed")
self.button.setText("Cancel optimization") // (2) self.button is the button stored in (1)
Option 2: QObject::sender
As mentioned in the comments, using QObject::sender may be an alternative to obtain the clicked button inside clickme.