How do I create a generic std::vector destructor?

Question

Having a vector containing pointers to objects then using the clear function doesn't call the destructors for the objects in the vector. I made a function to do this manually but I don't know how to make this a generic function for any kind of objects that might be in the vector.

void buttonVectorCleanup(vector<Button *> dVector){
    Button* tmpClass;
    for(int i = 0; i < (int)dVector.size(); i++){
     tmpClass = dVector[i];

     delete tmpClass;
    }
}

This is the function I have that works fine for a specific type of object in the vector but I'd like a single function that could take any kind of vector with object pointers.

Answer 1

The best thing to do is use smart pointers, such as from Boost. Then the objects will be deleted automatically.

Or you can make a template function

template <class T>
void vectorCleanup(vector<T *>& dVector){
    T* tmpClass;
    for(vector<T*>::size_type i = 0; i < dVector.size(); i++){
        tmpClass = dVector[i];

        delete tmpClass;
    }

}

Answer 2

A couple of other points - you probably want to pass a reference to the vector, not a copy. tmpClass is not needed - you can delete the pointer directly. You should either resize the vector to 0 or replace the pointers with NULL after deleting - otherwise you could access unallocated memory in the calling function.

Answer 3

You might want to use boost's pointer containers. They are highly efficient and safe.

Answer 4

I use a special functor to delete the pointer and set it to NULL:

struct delete_ptr
{
    template <typename T>
    void operator()(T& p)
    {
        delete p;
        p = 0;
    }
};

Which is used with std::for_each (also don't forget to #include <algorithm>):

int wmain(int, wchar_t*[])
{
    std::vector<int*> items;
    items.push_back(new int(1));
    items.push_back(new int(2));
    items.push_back(new int(3));
    std::for_each(items.begin(), items.end(), delete_ptr());
};