Question

I have a mother class that stores the pointers to some objects in a list. I want these objects to detach themselves from the list when they are destroyed.
Can anyone suggest some good ways to do this please?

Answer 1

The crude way is to store the container reference (or pointer) in the objects in the list and remove themselves in their destructors:

class Contained;
class Container {
  std::list<Contained*> children;
public:
  ...
  void goodbye(Contained*);
};
class Contained {
  Container& c; // you set this in the constructor
public:
  ~Contained() { c.goodbye(this); }
};

Note that this makes the Contained class non-copyable.

The easy way is to use some framework that already provides such functionality. Eg. if you use Qt, you would just derive the Contained class from QObject and store QPointer<Contained> in the Container. The QPointer would be set to zero once the contained object is deleted.

Or, if you use some memory management facilities like boost::shared_pointer, (I assume the Container doesn’t own the Contained objects, otherwise, it knows best when the child object dies), you would use a weak pointer in the Container, which has similar functionality.