Question

I have these classes:

class Base
{
...
private:
std::vector<X> v;
};

class Derived : public Base
{
Derived(X*, int n);
};

where the constructor of Derived is passed an array of item Xs, which I need to insert into my vector v in the Base class. (X is a smart pointer)

Currently I see two ways to do this:

1. Create a function in Base:
   InsertItem(X*) that will insert an
   item into the vector (1 by 1)
2. Create a vector in Derived that contains the
   full list, then get it into Base by
   moving the entire vector.

I dont see any advantages to #2, but was wondering if #1 was a good solution, or if there are better ways to do this.

Thanks!

Answer 1

There is a third option if you can modify Base. You could make the vector protected which will allow base classes full access:

class Base
{
...
protected:
    std::vector<X> v;
};

Your base class can now directly operate on v. If you need to expose much of the vector functionality to Derived, this is the easiest way.

If not, I would just add the one function (i.e. option #1) and would make it protected:

class Base
{
...

protected:
    void push_back(const X &x)
    {
        v.push_back(x);
    }

private:
    std::vector<X> v;
};