[Qt-interest] Howto: multiple emissions of signal cause one single slot execution.

[Davor J.]

William Crocker ask for an example. It's similar to his, but here it is:

class HandWaver {
    Q_OBJECT
public:
    HandWaver() : handRaised(false) {}

public slots:
    void raiseHand(){
        if (handRaised) return;

        /*... code to raise hand ... */

        handRaised = true;
        //If one wants the hand to be lovered on idle loop, one can 
uncomment this:
        //QTimer::singleShot(0, this, SLOT(loverHand()));
    }

    void loverHand(){
        if (!handRaised) return;

        /*... code to lover hand... */

        handRaised = false;
    }

private:
    bool handRaised;
};

"raiseHand()" is then connected to the raise() signal.

After writing this I am surprised how simple the solution is I was looking 
for... In my own case "raiseHand" = "dirtyFlag", and it's checked before 
starting the execution of a processintensive task.

Regards,
Davor

<william.crocker at analog.com> wrote in message 
news:4C122A16.6010704 at analog.com...
>
>>>
>>> Now the question: How would you execute "raiseHand()" only once in such 
>>> a scenario? (In other words: You don't want to raise the hand on every 
>>> single yell, but as a confirmation on all the yells, given a certain 
>>> happening.)
>>>
>
> void
> MyApp::raiseHand() {
>     if( ! m_RaisHandScheduled ) {
>         QTimer::singleShot(0, this, SLOT(doRealRaiseHand()));
>         m_RaiseHandScheduled = true;
>     }
> }
>
> void
> MyApp::doRealRaiseHand() {
>     ... really raise my hand ...
>     m_RaiseHandScheduled = false;
> }