passing SIGNAL from a object contained in another... is there a nicer way?

[pir]

Hi!

I'm just wonder how people normally do when they have a instance A lying in a instance B which lies in Frame C. Instance D lies in C and needs signals from A. But since A is not known by C or D, the signal from A must be passed by B... do I need to do like this:
( excuse the bad indentation on the code, I've tried to prettify it )

who knows who:
A<------B<------- [C]--------->D

propagation of signal a1:
[A: send SIGNAL a1 ]->[B: recieve in SLOT, pass SIGNAL b1 (saying the same thing)]-------------->D[recieves SIGNAL b1 which actually is a1]

/** class A ******************/
  class A{
     signals:
           void a1();
   }; class A
 
/** class B *******************/
class B{
 
  /** connect in constructor */
  B( )
    {
        connect ( &a, SIGNAL(a1()), this, SLOT(pass_signalA1()));
     }// B ( )
 
slots:
 
  /** a slot only passing the signal */
  void pass_signalA1()
    {
       emit b1();
     }// pass_signalA1()
 
 signals:
 
  /** the signal, actually the a1 signal passed on */
  void b1();
    A a;
   }; // class B
 
/*** class C **************/
class C{
 
  /** connect B and D */
   C ( ) 
   {
        connect ( &b, signal(b1()), &d, SLOT(Dslot()));
   }// C( )
 
B b;
D d;
}; //class C
 
/*** class D *****/
class D{
 
/** slot recieving the signal b1 */
slots:
   void Dslot();
 
};//class D

/** class A ******************/
  class A{
     signals:
           void a1();
   }; class A

/** class B *******************/
class B{

  /** connect in constructor */
  B( )
    {
        connect ( &a, SIGNAL(a1()), this, SLOT(pass_signalA1()));
     }// B ( )

slots:
  
  /** a slot only passing the signal */
  void pass_signalA1()
    {
       emit b1();
     }// pass_signalA1()

 signals:
 
  /** the signal, actually the a1 signal passed on */
  void b1();
    A a;
   }; // class B

/*** class C **************/
class C{

  /** connect B and D */
   C ( ) 
   {
        connect ( &b, signal(b1()), &d, SLOT(Dslot()));
   }// C( )

B b;
D d;
}; //class C

/*** class D *****/
class D{

/** slot recieving the signal b1 */
slots:
   void Dslot();

};//class D

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Maybe I should show some code instead, but I give this a chance.

[jacek]

You don't have to implement a slot to pass the signal, you can do this instead:

connect( &a, SIGNAL( a1() ), this, SIGNAL( b1() ) );

connect( &a, SIGNAL( a1() ), this, SIGNAL( b1() ) );

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Now whenever "this" receives the a1() signal, it will emit b1().

[pir]

nice, thanks! So it was worth the trouble writing this message after all.