strange connect

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?

Code:

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

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and why this connect get me a run time error:

Code:

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

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but this works:

Code:

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

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See if the _myw is null before u call the Connect

Code:

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

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

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.

Code:

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

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with this parent popup sould be myMainForm. true?

Quote:

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with this parent popup sould be myMainForm. true?

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

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

Anyone know this? thanks

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

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

Code:

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

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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

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:

Code:

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

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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.

Quote:

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Originally Posted by mickey

Code:

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

---

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