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Asked: 2026-05-25T11:59:43+00:00

I have a set of objects in a vector of pointers to their baseclass

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I have a set of objects in a vector of pointers to their baseclass held inside a manager:

std::vector<object*> objectVec;

Classes may wish to spawn one of these objects using the Add() method in the manager. The problem is that they then subsequently need to set or update these objects themselves. I’ve decided to have Add() return a pointer to the object itself, which is stored in whatever class has decided to spawn one. The problem is dealing with the case where the object behind that pointer may have been deleted.

Add looks like this:

object* ObjectManager::Add(object* obj)
{
   objectVec.push_back(obj);
   return objectVec.back();
}

and used like this:

objectptr = ObjectManager::OMan()->Add(new object());

Where objectptr is a member of whatever class has called the function. So should that particular object be deleted, the pointer returned by Add would point to rubbish.

Is it my responsibility to ensure that whateverclass::objectptr is always set to NULL if this object is deleted? Or can this be dealt with using some sort of smart pointer? The problem being that I don’t need to use a smart pointer to deal with the possibility of a memory leak, but to deal with the case where the stored pointer has become invalid.

Please let me know if i’ve been unclear, or if the question is badly formed.

Any help would be greatly appreciated.

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1 Answer

  1. Editorial Team

    You likely want weak_ptr and shared_ptr. shared_ptr is a general smart pointer class. weak_ptr is an observer of shared_ptr. When all the references of the shared_ptr go away, instances of weak_ptr “become null” and are easier to deal with than a pointer to a deleted object.

    These classes come with Boost.
    http://www.boost.org/doc/libs/1_47_0/libs/smart_ptr/shared_ptr.htm

    http://www.boost.org/doc/libs/1_47_0/libs/smart_ptr/weak_ptr.htm

    And if I’m not mistaken, there are equivalents built into std namespace on compilers that implement newer C++0x standards. Visual C++ keeps has this built in.

    http://blogs.msdn.com/b/vcblog/archive/2011/02/16/10128357.aspx

    Oh shoot, looks like everyone else beat me to the answer…

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