Give access to encapsulated container

Question

class X {
  public:
    typedef std::list Container;

    // (1)
    const Container& GetElements() const;

    // (2)
    Container::iterator Element         


        

Answer 1

If you can use Boost, there is a library for you: http://www.boost.org/doc/libs/1_47_0/libs/iterator/doc/index.html Specifically look at iterator_facade and iterator_adapter

Here is an example of what to do - It provides an std::vector holder, with STL compatible iterators. You can extend it by adding other methods, like operator[], size(), push_back() etc.

template class VectorHolder { public: typedef T value_type;

public: VectorHolder() : m_values() { }

public: typedef typename std::vector::iterator vector_iterator; typedef typename std::vector::const_iterator vector_const_iterator;

class iterator : public boost::iterator_adaptor
{
public:
    iterator()
        : iterator::iterator_adaptor_()
    {
    }

    iterator(const vector_iterator& it)
        : iterator::iterator_adaptor_(it)
    {
    }

private:
    friend class boost::iterator_core_access;
};

class const_iterator : public boost::iterator_adaptor
{
public:
    const_iterator()
        : const_iterator::iterator_adaptor_()
    {
    }

    const_iterator(const vector_const_iterator& it)
        : const_iterator::iterator_adaptor_(it)
    {
    }

    const_iterator(const iterator& it)
        : const_iterator::iterator_adaptor_(it.base())
    {
    }
private:
    friend class boost::iterator_core_access;
};


iterator begin()
{
    return iterator(m_values.begin());
}

iterator end()
{
    return iterator(m_values.end());
}

const_iterator begin() const
{
    return const_iterator(m_values.begin());
}

const_iterator end() const
{
    return const_iterator(m_values.end());
}protected:
std::vector m_values;};