# A demo of how to get notifications that text in a QLineEdit
# has been edited.
  
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
  
import sys
  
class Demo_QLineEdit(QDialog):
    def __init__(self, parent=None):
        QDialog.__init__(self, parent)
  
        self.setWindowFlags(Qt.WindowStaysOnTopHint)
        self.setWindowTitle("Demo QLineEdit")
        self.setFixedSize(400, 200)
        
        # Create the main vertical layout.
        vlayout = QVBoxLayout()
        self.setLayout(vlayout)    
        
        self.addLineEditPanel(vlayout)
        
        # Ensure the LineEditPanel is pushed to the upper edge of the
        # Dialog window.
        vlayout.addStretch()
        
        self.show()
    #--------------------------------------------------------------------
    def addLineEditPanel(self, parentLayout):
        self.textLine = QLineEdit()
        self.textLine.textChanged[str].connect(self.lineChangedAction)
        parentLayout.addWidget(self.textLine)
        
    #--------------------------------------------------------------------        
    # Activated by the text in the QLineEdit being edited.
    def lineChangedAction(self, text):
        print(text)
    #--------------------------------------------------------------------
# ========================================================                
if __name__ == '__main__':
    # Create the Qt Application
    app = QApplication(sys.argv)
    demo = Demo_QLineEdit() # <<-- Create an instance
    demo.show()
    sys.exit(app.exec_())