example.py

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QFormLayout, QSpinBox, QTextEdit, QVBoxLayout, QLabel
from PyQt5.QtGui import *
from PyQt5.QtCore import *
class spindemo(QWidget):
    def __init__(self, parent = None):
        super(spindemo, self).__init__(parent)
      
        layout = QVBoxLayout()
        self.l1 = QLabel("current value:")
        self.l1.setAlignment(Qt.AlignCenter)
        layout.addWidget(self.l1)
        self.sp = QSpinBox()
        
        layout.addWidget(self.sp)
        self.sp.valueChanged.connect(self.valuechange)
        self.setLayout(layout)
        self.setWindowTitle("SpinBox demo")
        
    def valuechange(self):
        print "hi"
        self.l1.setText("current value:"+str(self.sp.value()))

def main():
    app = QApplication(sys.argv)
    ex = spindemo()
    ex.show()
    sys.exit(app.exec_())
    
if __name__ == '__main__':
    main()