attributeError when calling method of object class

from PyQt5 import uic
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *

QApplication.setAttribute(Qt.AA_EnableHighDpiScaling)
app = QApplication([])
window = uic.loadUi("exercise2.ui")


class Car:
    def __init__(self):
        self.speed = 5

    def accelerate(self):
        if self.speed + 5 < 20:
            self.speed += 5
        return self.speed

    def decelerate(self):
        if self.speed - 5 >= 0:
            self.speed -= 5
        return self.speed

    def animate(self):
        currentX = window.car.x()
        window.car.setGeometry(currentX + self.speed, 30, 120, 70)


movingCar = Car()
timer = QTimer()
timer.timeout.connect(movingCar.animate)
timer.start(40)

window.accelerateButton.clicked.connect(Car.accelerate)
window.brakeButton.clicked.connect(Car.decelerate)

window.show()
app.exec_()

Trying to animate a car with button to accelerate and decelerate. When I press a button to accelerate/decelerate, I get an error in the ‘if’ statements on both methods “AttributeError: ‘bool’ object has no attribute ‘speed'”. Can someone help me figure out what’s going wrong? Thank you!

Answer

You should pass to clicked.connect a method bound to the object in question instead of the unbound method Car.accelerate:

window.accelerateButton.clicked.connect(movingCar.accelerate)
window.brakeButton.clicked.connect(movingCar.decelerate)