PyQT - Signals and Slots?

[Veek M]

Mark Summerfield wrote:

> 
> The ZeroSpinBox is a tiny example designed to show how the signal/slot
> mechanism works. It is just a QSpinBox with the addition of
> remembering how many times (all the) ZeroSpinBox(es) have had a 0
> value.
> 
> Nowadays the connections would be made with a new improved syntax:
> 
> self.connect(self, SIGNAL("valueChanged(int)"), self.checkzero) # OLD
> self.valueChanged.connect(self.checkzero) # NEW
> # or
> self.valueChanged[int].connect(self.checkzero) # NEW
> 
> Similarly the emit:
> self.emit(SIGNAL("atzero"), self.zeros) # OLD
> self.atzero.emit(self.zeros) # NEW
> 
> What's happening inside ZeroSpinBox? Whenever its value is set to 0 it
> calls its own checkzero() method, and this in turn emits an atzero
> signal with the number of zeros so far. Why does it do this? Just to
> show the mechanism. It doesn't matter whether you connect a widget to
> itself (unusual but done here), or to another widget (the norm).
> 
> See the book's website https://www.qtrac.eu/pyqtbook.html
> for all the source code including some updated with the new syntax.
> (But the book is old, so even the Python 3.1 examples aren't as
> Pythonic as they would be written in Python 3.4+.)

ah - okay, so i was on the right track - thanks :) cool that you hang 
out here :)