Why does pyqtSlot decorator cause “TypeError: connect() failed”?

Question

I have this Python 3.5.1 program with PyQt5 and a GUI created from a QtCreator ui file where the pyqtSlot decorator causes \"TypeError: connect() failed between textChanged(

Answer 1

Why do you want to use @pyqtSlot?

The reason it fails is that LineEditHandler is not a QObject. What @pyqtSlot does is basically creating a real Qt slot instead of internally using a proxy object (which is the default behavior without @pyqtSlot).