[Interest] Best way to invoke a slot after some time with QObject::sender

André Somers andre at familiesomers.nl
Tue Aug 28 09:21:37 CEST 2012

Op 28-8-2012 8:36, Till Oliver Knoll schreef:
> Am 28.08.2012 um 04:10 schrieb Preet <prismatic.project at gmail.com>:
>> Hiya,
>> I have a project where I'm trying to asynchronously reply to a signal.
>> So if ObjectA sends ObjectB a signal, ObjectB will send ObjectA a
>> reply signal at some later point in time.
> That sounds like "broken by design" to me: you'd have a dependency circle here! In order to *connect* to a signal you have to *know* the signal emiter's class. So signals should only go one way: bottom up.
> That said, your problem sounds a little bit what QNetworkAccessManager is solving: you have multiple clients that request (by method call!) something from the network, they get a handle (object) for the time being (with which they can also e.g. abort the current operation), the QNAM does its work asynchronously and finally emits a signal (actually several ones in each state transition) once it's done (it doesn't know its clients though!).
> Why wouldn't that approach work in your case?
QFuture and QFutureWatcher are also designed for such tasks, but 
unfortunately it only works with the Qt Concurrent framework..


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