How to erase elements from boost::ptr_vector

Question

So I\'m trying to get rid of my std::vector\'s by using boost::ptr_vector. Now I\'m trying to remove an element from one, and have the removed element deleted as well. The m

Answer 1

Well you can do that with a std::vector either.

In both cases erase takes an iterator as a parameter.
So before you can erase something from a vector (or a ptr_vector) you need to locate it.

Also note that the ptr_vector treats its content as if you have stored an object not a pointer. So any searching is done via the object.

So basically

 std::vector       x;
 std::ptr_vector   y;

 // These two object should behave in exactly the same way.
 // The ONLY difference is inserting values which for y are pointers.
 // Y take ownership of the pointer and all subsequent acesses to the
 // members of y look like they are objects

Example:

#include 
#include 

class A
{ int m;
    public:
    A(int x):m(x)   {}
    bool operator==(A const& rhs)   {return m = rhs.m;}
};

int main()
{
    boost::ptr_vector    x;
    x.push_back(new A(1));
    x.erase(std::find(x.begin(),x.end(),A(1)));


    std::vector          y;
    y.push_back(A(2));
    y.erase(std::find(y.begin(),y.end(),A(2)));

    // To find an exact pointer don't modify the equality.
    // Use find_if and pass a predicate that tests for a pointer
    A* a = new A(3);
    boost:ptr_Vector     z;
    z.push_back(a);
    z.erase(std::find_if(y.begin(),y.end(),CheckPointerValue(a));
}

struct CheckPointerValue
{
     CheckPointerValue(A* a):anA(a) {}
     bool operator()(A const& x)    { return &X == anA;}
     private:
        A* anA;
};