[Qt-interest] Qt signaling smarts...

[Gordon Schumacher]

Thiago Macieira wrote:
> Remember that an auto connection is queued if the *target* object is in a 
> different thread. If objects B and C are in the main thread, and you have the 
> connection A→B→C and you emit A's signal in the auxiliary thread, it would 
> originally cause the first connection to be queued and the second one would be 
> DirectConnection. If you force the first one to be direct, B's signal is 
> emitted in the auxiliary thread. Buy then the second connection becomes queued 
> because C is in a different thread.
>   

Ah - I think I over-complexified my idea of what was going on; I was
imagining that B was the QApp thread, and A and C were each in their own
threads.

> There is still a small race condition if you connect or disconnect in one 
> thread while the other emits. No crash will happen, but you may be surprised 
> that the connection gets emitted (or not) when you weren't expecting.
>   

...and as long as you're doing things "right", that shouldn't be an
actual problem.