How to identify event sender?

Hi,
I have several widget handling different parameter settings, which are all connected to the same slot. So I need to know which widget has sent a signal so as to process the event properly in the slot code. How could I proceed? one idea I had was to add an int identificator in the event, but the signal format cannot be changed (for instance QSlider signal valueChanged() only admit a sigle int argument). Since i suppose that this issue is somehow common, how do u cope with it?
Thanks in advance for your answer.

Caius