[Qt-interest] signals / slots

[Thiago Macieira]

On Tuesday, 11 de January de 2011 11:01:07 Michael S wrote:
> Good day all,
> 
> I am writing a service type console application and decided to use signals /
> slots for event notifications. I have a few times of events. Some are
> scheduled with QTimer objects, some are external. I was wondering if the
> emitted signals get queued somewhere, in case 2 of them overlap and the
> first slot takes a long time to complete. In other words I want to make
> sure than no signals are lost.

No signals are ever lost.

It seems you misunderstand how signals and slots work. There's nothing 
asynchronous, there are no other threads (other than what you start).

Signals and slots[*] are nothing more than a glorified callback mechanism. When 
you emit a signal, it's like you were calling each and every slot, in 
sequence. So there's simply no way another signal can intervene and stop the 
processing. 

You can have a signal be emitted from inside a slot, but it's like a different 
callback is being invoked.

[*] this can change with queued connections, but it doesn't seem this concept 
is relevant here.
-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
      PGP/GPG: 0x6EF45358; fingerprint:
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