relaying signals

Hello!

Here is the situation. Object A has a B and B has a C (A -> B -> C). C emits signals that are actually meant for A, but A doesn't know about C, so I can't connect() the signals from C to A in A. B knows about C, but it doesn't know about A, so I can't connect() C to A there either. For now the only solution I see is connecting C to B and reemitting the signal from B to A. Isn't there something better I can do?

Thanks
Cruz

You do not need to reemit signal yourself. You can connect signal of C to signal of B. And if you connected signal of B to A's slot, you will automatically receive emit of C's signal

Code:

---

B::B()
{
  connect( &c, SIGNAL( c_signal_signature ), SIGNAL( b_signal_signature ) );
}
 
A::A()
{
  connect( &b, SIGNAL( b_signal_signature ), SLOT( a_slot_signature ) );
}

---

Quote:

---

Here is the situation. Object A has a B and B has a C (A -> B -> C).

---

As far as I understand its something like -

Code:

---

class A
{
 B objB;
};
 
class B
{
C objC;
}
 
class C
{
}

---

If thats the case, you need to provide a function in B to return objC. say C* B::getObjC()
Then in class A or whereever you can connect

Code:

---

connect(objB->getObjC(), SIGNAL(), this, SLOT());
connect(objA->getObjB()->getObjC(), SIGNAL(), objA, SLOT());

---

If above is not ur required hierarchy, please mention with class structure.

aamer4yu, Cruz said:

Quote:

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but A doesn't know about C

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I understood it that A knows NOTHING about C.
that's why connecting C's signal to B's signal, and connecting B's signal to A's slot - it seems to me the right idea. Isn't it ?

"You can connect signal of C to signal of B." - yeah thanks, I wasn't aware of this. This solution is satisfactory.

Quote:

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I understood it that A knows NOTHING about C.

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I even didnt say A knows anything about C... but in some way A knows that it has to perform some operation based on a given signal.
It depends on where you perform the connect operation. If you connect in main window class,, then I guess it may know about A,B and C.

I just gave a way where you need not put extra signal in class B. Just imagine if A->B->C->D->E->F->G was the case, and you wanted to emit signal from G and process in A... what technique would you have used ?
Would you put a signal all the way from B to F ??

Quote:

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Originally Posted by aamer4yu

Would you put a signal all the way from B to F ??

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Good point. However, the solution you suggested requires that A knows about C, or about G in the case of the extreme example.

Code:

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connect(objA->getObjB()->getObjC(), SIGNAL(), objA, SLOT());

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requires A to include C's header so that it knows about its signals, right? And that's also not very pretty, because B was supposed to hide C from A. So if neither this, nor the signal relaying are perfectly clean solutions for this kind of problem, what else can be done?

Quote:

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requires A to include C's header so that it knows about its signals, right?

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Not necessarily,,, you can make the connection from your main class,,, which knows about A,B and C.
Also if you are making connection inside A, then A in someway knows about the signal, doesnt it ?? atleast the name and signature :rolleyes: