[SOLVED] Connecting signal and slot between parent and "grandchild"

rizoritis

Hello,

I have an application with a main widget (parentWidget). Within my main widget I create a new widget (we can call it childWidget). Within childWidget I create a new widget (call it grandchildWidget). I want to connect a signal from my grandchild to my parent widget. I tried using:

@connect(this, SIGNAL(updateGeneralStatusSignal()), this->parent()->parent(), SLOT(updateGeneralStatusSlot()));@

however, this did not work. I have been able to use this->parent() between the parent and child widget, but it wont allow me to do it between the parent and grandchild.

Any thoughts?

Thanks

SGaist

Hi,

You're doing it the wrong way.

You should emit, if necessary chain the emit in the child widget, and connect the childWidget signal in parentWidget.

i.e.

@
parentWidget.cpp:
connect(childWidget, SIGNAL(updateGeneralStatusSignal()), SLOT(updateGeneralStatusSlot()));

childWidget.h:

class ChildWidget : public QObject
{
Q_OBJECT

public:

signals:
void updateGeneralStatusSignal();
}

childWidget.cpp:
connect(grandChild, SIGNAL(updateGeneralStatusSignal()), SIGNAL(updateGeneralStatusSignal()));
@

Your grandChild widget should not care about connecting other widgets to him. Otherwise you'll break orthogonality.

It's the object who knows where the signal should go the should the connections.

dbzhang800

Hi,

IMO, the reason is that, this->parent()->parent() isn't the widget as you expected. You can output the result of

@
this->parent()->parent()->metaObject()->className()
@

BTW, usually it's not good to use this style for widgets in a real application, as it's hard to maintain. You can pass the pointer of the expected widget to your current widget.

rizoritis

[quote author="SGaist" date="1373559965"]Hi,