Listener implementation method

Hi Experts,
I have an object with few attributes.  The attributes are strings, int, or anotherObject. Interested parties should register listeners for a particular attribute. For example, if someone is interested in attrOne should call addListener( ) indicating it.   How can I implement this?  I am looking for some pseudo code type advice.  

I was thinking may be I should add an enum to the class, like
enum{ ATTRIB_ONE, ATTRIB_TWO, ATTRIB_THREE, ATTRIB_FOUR }
and then the listeners will be calling like
addListener(Object.ATTRIB_ONE, callback );
Is that a good way?

Thank you very much.

class Object
{
   public:
     String attrOne;
     String attrTwo;
     int  attrThree;
     anotherObject attrFour;
    
     void addListener( , callback );
     void removeListener( );
     void notifyListeners( );
}

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