Re: Passing variables up to the GUI

[Daniel J Sebald]

On 04/14/2013 04:17 PM, Daniel J Sebald wrote:
> On 04/14/2013 03:19 PM, Michael Goffioul wrote:
[snip]
> > "Later" is irrelevant here. With multithreaded app, both destructors can
> > happen at the same time, concurrently.
>
> But when is that in the QThread environment? Not generally speaking in
> the OS environment. The important thing here is the signal/slot
> mechanism. It may be that in order for this to operate properly, the Qt
> programmers took an approach whereby the constructor-copy and delete are
> done in the same thread. For example
>
> GUI issued signal
>    copy object in GUI thread
>    call all slots in the Worker thread
>    delete object in the GUI thread
>
> Worker issue signal
>    copy object in the Worker thread
>    call all slots in the GUI thread
>    delete object in the Worker thread

I just thought that in fact it can be a mix of connections and more 
complicated:

Worker issue signal
  call all slots in the Worker thread using direct?
  copy object in the Worker thread
  call all slots in the GUI thread using queuing?
  delete object where????

Point being that it is complex enough to make one wonder where exactly 
the copy/delete is done and whether Qt programmers had to so something 
very safe inside of this signal/slot mechanism.

Dan