[Qt/C++] How to manually cause a signal of another control to emit ??

Question

I wanted to know if its possible to emit some specific signal through coding .. For example, I want to emit another button's clicked event without the user actually clicking that button .. can do I do this ?

Answer 1

Signals are internally implemented as C++ private member functions, so I'd advise against doing so.

Answer 2

You could call that other button's click function. It will emit the clicked signal.

Answer 3

Qt, throught the moc, implement the emit keyword, that allow you to emit signals throught coding.

If the Class that you are using doesn't provide a method for emit some signal, you can Subclass it, and implement a function that does it yourself. But I must say that I had never done this for "normal" signals. Only did it when I defined my own signals in some class extension.

Answer 4

Instead of emitting the signal by yourself and connecting it to the slot, why cant you call the slot directly? Slots are just like other C++ functions, in the sense that you can call it directly. I don't see any reason where you have emit a predefined signal (like clicked()). Just call your slot directly.

Answer 5

to emit a signal you just write

emit signalName(param list);

#include <QObject>

 class myClass : public QObject
 {
     Q_OBJECT

 public:
     myClass (QObject *parent = 0) : QObject(parent) { }
     void foo();

 signals:
     void mySignal(int param);
 };

void myClass::foo() { emit mySignal(5); }

read more at http://doc.trolltech.com/4.6/signalsandslots.html

you can also connect a signal to another signal so you can connect mysignal to the buttons clicked signal and when your signal is emited the clicked signal will also be emited see http://doc.qt.nokia.com/4.6/qobject.html#connect