strange connect

[mickey]

I've problem: this connect get me a console error like as cannot connect check box to null::set(bool); but the SLOT starts; it works!Why?



FancyPopup::FancyPopup(myMainForm* parent, const char* name ):
QLabel( parent, name, WType_Popup ), _myw(parent){
connect (checkBox, SIGNAL(toggled(bool)), _myw, SLOT(set(bool)));


and why this connect get me a run time error:


connect (dial, SIGNAL(valueChanged(int)), _myw, SLOT(setValue(int)));

but this works:


connect (dial, SIGNAL(dialMoved(int)), _myw, SLOT(setValue(int)));

[sunil.thaha]

See if the _myw is null before u call the Connect

[mickey]

FancyPopup::FancyPopup(myMainForm* parent, const char* name ):
QLabel( parent, name, WType_Popup ), _myw(parent){

yes, _myw in null; but why??? I set its parent to myMainForm* in costructor how above. How can it be null?

[sumsin]

What you are passing in the constructor of the FancyPopup?

I think you are calling the constructor by default values and the default value for myMainForm* parent is zero.

Thats why _myw is null.

[mickey]

myMainForm::myMainForm( QWidget* parent, const char* name, WFlags fl )
: MainForm( parent, name, fl )
{
popup = new FancyPopup(this);

with this parent popup sould be myMainForm. true?

[sumsin]

with this parent popup sould be myMainForm. true?

yes. Now the parent of your FancyPopup is myMainForm, as you are passing 'this'.

[mickey]

OK! my code is that before! Why parent is null???

[mickey]

Anyone know this? thanks

[jacek]

Maybe you have two _myw variables and you initialize the first one, but use the other one?

[mickey]

the instance of popup is created in myMainForm but the connect are linked inside costructor of Popup;


FancyPopup::FancyPopup(QWidget* parent, const char* name ):
QLabel( parent, name, WType_Popup ){
_myw = (myMainForm*) parent;

with this above _myw was null......I putted connect inside costructor of myMainForm and works; but I still don't understand why didn't work first...
thanks

[sumsin]

As your FancyPopup is inherited from the QLabel and when you have declare the constructor of the FancyPopup in the header file, I think you have passed the defaults values for the arguments of the constructor.

Like this:



FancyPopup(QWidget* parent = 0, const char* name = 0 );


So when you try to create an instance of FancyPopup without arguments, it takes the default values. And thats why your parent is NULL in first case.

[mickey]

myMainForm::myMainForm( QWidget* parent, const char* name, WFlags fl )
: MainForm( parent, name, fl )
{
popup = new FancyPopup(this);


mmmm sorry but here above I created an instance of FancyPopup with argument 'this'; then how its parent is null? thanks