Std :: conditional value in nested template

Question

I am trying to implement an STL style RingBuffer. This means that I also execute an iterator for it, which should work both const and not const. This is only part of the iterator:

#include <iterator>
#include <type_traits>

template <typename T> class RingBuffer {
public:
    class Iterator;
    // actual RingBuffer implementation here
};    

template <typename T, bool is_const=false> 
class RingBuffer<T>::Iterator {
public:
    typedef std::ptrdiff_t difference_type;
    typedef T value_type;
    typedef typename std::conditional<is_const, const value_type*, value_type*>::type pointer ;
    typedef typename std::conditional<is_const, const value_type&, value_type&>::type reference ;
    typedef std::random_access_iterator_tag iterator_category;

    // a bunch of functions here
    ...
};

GCC 4.8.0 gives errors for every line where I try to access the iterator by saying something like

no type named 'type' in 'struct std::conditional<is_const, const int*, int*>'

Substitution intfor the type with which the instance was created RingBuffer<T>. I do not understand. is_consthas a default value. Why is this not working? And why doesn't GCC sign in falsein the error message, for example, does it replace intwith value_type?

The solution is probably obvious, but all the search engines in the world have not taken me anywhere. Patterns are still confusing me.

Answer 1

, Iterator templated bool is_const, :

template <typename T> class RingBuffer {
public:
    template <bool is_const = false>
    class Iterator;
    // actual RingBuffer implementation here
};    


template <typename T>
template <bool is_const> 
class RingBuffer<T>::Iterator {
public:
    typedef std::ptrdiff_t difference_type;
    typedef T value_type;
    typedef typename std::conditional<is_const, const value_type*, value_type*>::type pointer ;
    typedef typename std::conditional<is_const, const value_type&, value_type&>::type reference ;
    typedef std::random_access_iterator_tag iterator_category;

    // a bunch of functions here
    ...
};

: Iterator , Iterator . RingBuffer , T; Iterator ; is_const. , :

class Foo;

template <bool b = false>
class Foo
{
  // something
};

, , .