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View Full Version : How to connect a signal from class a to a slot in a class b?



mekos
17th September 2008, 21:15
Hello
i have this connection:


//Class A
connect( treeWidgetA, SIGNAL( clicked( const QModelIndex& ) ), this, SLOT( doSomething(const QModelIndex& ) ) );


I have to move the doSomething slot in B class too, and i want to connect the B's class treeWidget signal clicked, to the slot doSomething that already exists in class A.is it correct?



//Class B
AClass *aClass;//is it correct?
connect( treeWidgetB, SIGNAL( clicked( const QModelIndex& ) ),aClass , SLOT( doSomething(const QModelIndex& ) ) );


This approach is not working..am a declaring Aclass wrong in the B's class code?

*the slot doSomething is declared as public slot in class A*

Thanks!

spirit
17th September 2008, 21:28
you must use operator new for creating pointer to an object, so it should look like this


AClass *aClass = new AClass();
...

mekos
17th September 2008, 21:45
i've tryed that too.. (declared the aClass within B's Class constructor).Never goes into the slot in the class A..however there are no complaints in the "compiler such as QObject::connect:No such slot etc etc"..just never gets into the slot to execute the code..can't undertand whats going on..

spirit
17th September 2008, 21:48
did you add Q_OBJECT macro to both classes?

mekos
17th September 2008, 21:50
yes in both headers..

spirit
17th September 2008, 21:54
ok. can you prepare compilable example and post it? (if yes, can you put it in archive)

mekos
17th September 2008, 22:31
ok did it..
i have a slot in the first form which writes text to the editbox and i just want to use the same slot in form2 to change the editbox in form2

spirit
17th September 2008, 22:46
so, the problem is in ctor of Form2, you create a new instance of Form


...
Form *frm1=new Form;
...


but don't show it.
so, the right code is


...
Form *frm1=new Form;
frm1->show();
...

but, I strongly suggest you to review your code and make it more clearer.

mekos
18th September 2008, 00:35
no the problem is not the form.The second form shows up correct..The problem is with the slot testSLot() implemented in Form.cpp, that i want to use it and in form2.cpp

aamer4yu
18th September 2008, 06:39
I guess u want that from Form2 pushbutton, u want to send a signal to the parent form.
Am i right ?
In that case u will have to connect the signal slot in OpenForm2() function.

connect ( frm->pushButton, SIGNAL ( clicked() ), this, SLOT ( testSlot() ) );

mekos
18th September 2008, 12:26
That's right..now when i click the button in form2 the slot sets the text in form1..however i need a way to use the testSlot to set the text in form2 when i click form2's pushbutton and not form1.Basically i need one slot to do the same thing in two different forms..Is that possible since the components in the 2 forms have the same names?

aamer4yu
18th September 2008, 13:41
Then write the same function in Form2 class.

What you ask is not possible. Its like 2 classes sharing same function !! Is that possible ??

mekos
18th September 2008, 16:04
Thats the way i had it..i had 4 functions in A class and exactly the same functions in class B.But with this i had 500 lines of code in class A repeated in class B and i was wondering if there is a way to write the code in one class and use the same code in another class..so nevermind i'll write the same code in the other class too..

Thanks!