QT4:connect() with lambda function, compiled error:QThread::started() is protected

Asked Aug 14 '18 at 09:55

Active Aug 14 '18 at 10:02

Viewed 318 times

i am working on qt for a p2p gui, while i am trying to add connect to a lambda function, the compiler throw error complaining: 'void QThread::started()' is protected, however i can find no clues to fix this, please help me out, thx a lot. The context code is:

this->ip[3][20] = {"11.23.12.1","11.23.12.2","11.23.12.3"}; 
int i = 0;
this->p2p[i] = new p2p(); 
this->p2p_thread[i] = new QThread();
this->p2p[i]->moveToThread(this->p2p_thread[i]);
QObject::connect(this->p2p_thread[i], &QThread::started,
                 this->p2p[i], [=] {this->p2p[i]->p2p_decode(&this->ip[i][0]);});
this->p2p_thread[i]->start();

edited Aug 14 '18 at 10:02

asked Aug 14 '18 at 09:55

D.pz

4

You appear to be using the [`Qt5` `connect` syntax](https://wiki.qt.io/New_Signal_Slot_Syntax) with `Qt4`. That won't work. – G.M. Aug 14 '18 at 10:12
but i see a very similar use of connect with lambda function in http://doc.qt.io/archives/qt-4.8/qthread.html#finished – D.pz Aug 14 '18 at 11:01
1

I don't think that doc. example is correct. It's certainly not, as far as I can see, in the [latest `Qt4.8` source I can find](https://download.qt.io/archive/qt/4.8/4.8.7/). – G.M. Aug 14 '18 at 12:38
@D.pz That's a crazy documentation problem of some sort. – Kuba hasn't forgotten Monica Aug 14 '18 at 21:28
@G.M. thanks a lot, maybe i should try mapper – D.pz Aug 15 '18 at 02:50
The answer you're looking for is [the "backport" of Qt 5 functionality to Qt 4](https://stackoverflow.com/a/45244152/1329652). – Kuba hasn't forgotten Monica Aug 15 '18 at 03:10

QT4:connect() with lambda function, compiled error:QThread::started() is protected

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