Запуск функции без нажатия кнопки

# -*- coding: utf-8 -*-
 
import sys
 
from PySide2.QtWidgets import QApplication, QWidget, QSpinBox
from PySide2.QtGui import QKeyEvent
from PySide2.QtCore import Qt, QTimer
 
 
class Example2(QSpinBox):
 
    def __init__(self, parent:QWidget=None)->None:
        QSpinBox.__init__(self, parent)
        self.setWindowTitle("Example2")
 
        self.__timer = QTimer(self)
        self.__timer.setSingleShot(True)
        self.__timer.timeout.connect(self.__calc)
 
        if not parent: self.show()
 
    def __calc(self):
        value = self.value() + 20
        self.setValue(value)
 
    def keyPressEvent(self, event:QKeyEvent)->None:
        if self.__timer.isActive():
            self.__timer.stop()
        self.__timer.start(2000)
        return QSpinBox.keyPressEvent(self, event)
 
class Example3(QSpinBox):
 
    def __init__(self, parent:QWidget=None)->None:
        QSpinBox.__init__(self, parent)
        self.setWindowTitle("Example3")
 
        if not parent: self.show()
 
    def __calc(self):
        value = self.value() + 20
        self.setValue(value)
 
    def keyPressEvent(self, event:QKeyEvent)->None:
        if event.key() == Qt.Key_Enter:
            self.__calc()
        return QSpinBox.keyPressEvent(self, event)
 
if __name__ == '__main__':
    app = QApplication(sys.argv)
    example2 = Example2()
    example3 = Example3()
    sys.exit(app.exec_())

self.ui.lineEdit_8.textChanged[str].connect(self.top)