Signals and Slots - Summerfield - what exactly is a signal?

[Steve D'Aprano]

On Sun, 6 Aug 2017 12:28 am, veek wrote:

> 1. What exactly is a signal. In hardware, an interrupt can be viewed as a
> signal and the voltage on a pin will suddenly jump to +5V as an indicator
> that an interrupt has occurred. With Qt signals - if a widget-c++ code has
> to 'signal' an event - what does it do?

I don't know what Qt signals are.

Unix signals are an interrupt mechanism used by Unix and Linux operating
systems. Windows may support them as well. The "kill" system command sends
signals to a specific running process, which will then jump to a specific piece
of code. The command is called "kill" because the main use for this is to
terminate processes.

Python supports these signals:

https://docs.python.org/3/library/signal.html

https://pymotw.com/3/signal/index.html


 
> As a consequence of not understanding the above..
> 
> 2. How do you connect a single signal to multiple slots? Do the
> slots/methods get called one by one? or are they treated as independent
> threads and run on different cores?

What are slots?


> 3. pg 130 of Summerfield

What is Summerfield?





-- 
Steve
“Cheer up,” they said, “things could be worse.” So I cheered up, and sure
enough, things got worse.