Handling one object in some containers

Question

I want to store pointers to one instance of an object in some (two or more) containers. I've met one problem in this idea: how I can handle removing of this object. Objects have rather stormy life (I am talking about game, but I think this situation is not so specific) and can be removed rather often. To my mind this problem is divided into two problems

1. How should I signal to containers about deletion? In C# I used to create boolean property IsDead in stored objects, so each iteration of the main loop at first finds 'dead' objects and removes them. No circular reference and everything is rather clear :-) Is this technique correct?

2. Even if I implement this technique in C++ I meet difficulty with calling destructors if this object is in some containers. Even if I create some kind of a field 'IsDead' and remove dead object from all lists, I had to free memory.
After reading some articles I have an idea that I should have one 'main' container with shared_ptr to all my objects, and other containers should store weak_ptr to them, so only main container checks object's status and others look only at shared_ptr. Are my intentions correct or is there another solution?

Answer 1

It sounds like you're looking for shared_ptr<T>.

• http://msdn.microsoft.com/en-us/library/bb982026.aspx

This is a reference counted ptr in C++ that enables easy sharing of objects. The shared_ptr<T> can be freely handed out to several objects. As the shared_ptr instances are copied around and destucted the internal reference counter will be updated appropriately. When all references are removed the underlying data will be deleted.