One signal more slots

Hi,
I've a manager who handles more objects, each of them lives in a different thread.
During the creation of this objects, I connect a signal of a manager to a slot of the objects.

My goal is to emit a signal from manager and execute only one object slot.

I think I can enumerate all the objects and then invoke a signal with a parameters than identify the number of the object.
So every object receive the signal but when compare the signal parameter, only one object execute the slot.

I think this is a simple solution, but I don't think it's the best, in particular If I've a large number of objects.

Do you have any solutions?

Thanks

You can just keep a pointer of all objects in the manager and use a QHash using the id parameters to make a key

Code:

---

struct Object
{
  void bar(){/* do nothing */}
};
 
class Manager
{
  QHash<Key, Object*>  map;
 
  void foo()
  {
    // do something with 'key's object:
    Key key;
    map[key]->bar(); // no need to run method for each key/object
  }
};

---

I can't do this cause the object lives in different threads.

I've something like this:

Code:

---

class Manager : public QObject
{
    Q_OBJECT
 
    signals:
         void invokeObjMethod(int);
 
    private:
        void initManager(){
 
            for ( int idx = 0 ; idx < n; idx++){
                QThread * th = new QThread(this);
                MyObject * obj = new MyObject(idx);
                connect(this,SIGNAL(invokeObjMethod(int)),obj,SLOT(doSomething(int)));
                obj->moveToThread(th);
                th->start();       
           }
       }
}
 
class MyObject : public QObject
{
      Q_OBJECT
      public:
          MyObject(int idx, QObject * parent = 0)
                :QObject(parent),
                m_index(idx){}
 
     private:
          int m_index;
 
     public slots:
          void doSomething(int idx){
                  if ( idx != m_index)
                        return;
 
                  ...do Something ...
           }
}

---

When the manager emit the signal invokeObjMethod(int) all the objects invoke their slot but only one do something.
I want to know if this is the right way or there are other best solu

QSignalMapper?

The QSignalMapper class bundles signals from identifiable senders.
In my case I've only one sender.
I think that is not possible to use QSignalMapper in my case.

Am I wrong?

You are right. QSignalMapper cannot help you here.

There is a simple solution to your problem: QMetaObject::invokeMethod(). No more indices, just do something like

Code:

---

QMetaObject::invokeMethod(pointerToTheMyObjectInstance, "doSomething", Qt::QueuedConnection);

---

With this method I can directly call the thread slot of the single object, with QueuedConnection (safety for thread).

I think it's the best solution....many thanks!!!

Quote:

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Originally Posted by paolom

I can't do this cause the object lives in different threads.

---

Yes you can, just use invokeMethod and use it with a queued connection slot.