C++ when and how are std::iterator value_type, reference, pointer used?

Question

I'm writing a collection of containers and iterators for an environment where STL and Boost are off the table. I'm struggling somewhat with dealing with containers, such as a Vector, that can contain both value types and pointer types, when it comes to handling iterators and their return types - via a GetValue function, for example. It is further complicated by wanted to support const iterators. I have seen here about the definition of a series of traits: value_type, reference, pointer. My question is how are these used in the context of creating iterators? Essentially, given that I want

Object & Vector<Object>::Iterator::GetValue()
Object * Vector<Object*>::Iterator::GetValue() 
const Object & Vector<Object>::ConstIterator::GetValue()
const Object * Vector<Object*>::ConstIterator::GetValue()

How do value_type, reference, pointer factor into this?

Answer 1

The member types of iterators aren't used for very much. Fortunately, you don't need to bother defining them. The std::iterator base class does it for you.

template< typename value_type >
struct my_vector_iterator
    : std::iterator< std::random_access_iterator_tag, value_type >
    …

template< typename value_type >
struct my_vector_const_iterator
    : std::iterator< std::random_access_iterator_tag, value_type const >
    …