How to emit signal from static method?

[kusumat]

Hi I have tried to emit signal from static method in this way .

MainWidget* pThis;
MainWidget *MainWidget:: _instance = 0;
 
MainWidget::MainWidget(QWidget *parent):QWidget(parent)
{
  pThis = this;
}
MainWidget* MainWidget::getInstance()
{
    if(!_instance)
        _instance = new MainWidget();
    return _instance;
}
void MainWidget :: emitMySignal(){
     qDebug()<<"emitMySignal";
   pThis->emit mySignal ();
}
 MainWidget::~MainWidget()
{
 
}

MainWidget* pThis;
MainWidget *MainWidget:: _instance = 0;

MainWidget::MainWidget(QWidget *parent):QWidget(parent)
{
  pThis = this;
}
MainWidget* MainWidget::getInstance()
{
    if(!_instance)
        _instance = new MainWidget();
    return _instance;
}
void MainWidget :: emitMySignal(){
     qDebug()<<"emitMySignal";
   pThis->emit mySignal ();
}
 MainWidget::~MainWidget()
{

}

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and the call to static function and signal slot connection is here

MainWidget::getInstance()->emitMySignal();
      qDebug()<<"after emitCall back....";
      QObject::connect(MainWidget::getInstance(),SIGNAL(mySignal()),this,SLOT(connectToSlot()));

MainWidget::getInstance()->emitMySignal();
      qDebug()<<"after emitCall back....";
      QObject::connect(MainWidget::getInstance(),SIGNAL(mySignal()),this,SLOT(connectToSlot()));

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But this is not happening for me .
Plz suggest

[mcosta]

you connected the slot after emitted the signal.

try with

QObject::connect(MainWidget::getInstance(),SIGNAL(mySignal()),this,SLOT(connectToSlot()));
MainWidget::getInstance()->emitMySignal();
qDebug()<<"after emitCall back....";

QObject::connect(MainWidget::getInstance(),SIGNAL(mySignal()),this,SLOT(connectToSlot()));
MainWidget::getInstance()->emitMySignal();
qDebug()<<"after emitCall back....";

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what is the static method??

[Santosh Reddy]

pThis = this; //pThis is global, don't do this, you never know what it contains unless, ctor as private
 
void MainWidget :: emitMySignal(){ //I assume this is non static function, if not make it non-static function
     qDebug()<<"emitMySignal";
   //pThis->emit mySignal ();
    emit mySignal(); //this will work
}

pThis = this; //pThis is global, don't do this, you never know what it contains unless, ctor as private

void MainWidget :: emitMySignal(){ //I assume this is non static function, if not make it non-static function
     qDebug()<<"emitMySignal";
   //pThis->emit mySignal ();
    emit mySignal(); //this will work
}

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[high_flyer]

You can't emit signal from static methods, because static methods are not part of an objects instance, they are global, in the scope of the class, which means, you don't have a "sender" object for them.
You could send an event though.