error C2679: binary '=' : no operator found which takes a right-hand operand of type 'RX::FastSet<BASE>::sortedAppender' (or

The problem occurs in Visual Studio 2005 but works in Vc++6.0

rx_fastset.h

struct SortedAppender

typedef Std:: output_iterator_tag iterator_category;

typedef BASE value_type;

typedef ptrdiff_t difference_type;

typedef BASE* pointer;

typedef BASE& reference;

sortedAppender& operator=(value_type v) { m_fastSet.sortedAppend(v); return *this;}

sortedAppender& operator*() { return *this; }

sortedAppender& operator++() { return *this; }

sortedAppender& operator++(int) { return *this; }

rx_vist.cpp

inline

void SetUnion(const NodeIdSet& leftSet, const NodeIdSet& rightSet, NodeIdSet& unionSet)

Any help in this would be grateful.

Jonathan:

Let me Explain Clearly. This is the part of the Code where the error Happens

inline
void SetUnion(const NodeIdSet& leftSet, const NodeIdSet& rightSet, NodeIdSet& unionSet)
{
assert(unionSet.empty());
std:et_union(leftSet.begin(), leftSet.end(),
rightSet.begin(), rightSet.end(),
NodeIdSet:ortedAppender(unionSet));
}

if I comment this part of the code, it compiles.

/* std:et_union(leftSet.begin(), leftSet.end(),
rightSet.begin(), rightSet.end(),
NodeIdSet:ortedAppender(unionSet));

*/

There is a problem here and Error is described previously.

Let me give you the exact class definitions

namespace RX
{
template <class BASE>
class FastSet
{
private:
typedef std::vector<BASE> SetType;

public:
typedef typename SetType::iterator iterator;
typedef typename SetType::const_iterator const_iterator;
typedef typename SetType::const_reference const_reference;
typedef typename SetType::value_type value_type;

FastSet() {}
FastSet(const FastSet& original): m_set(original.m_set) {}
FastSet(const SetType& original): m_set(original) {}

void clear();

bool empty() const;

size_t size() const;

size_t max_size() const;

void sortedAppend(value_type);
void unique();

void swap(FastSet& fastSet);

iterator begin();
iterator end();

const BASE& operator[](unsigned) const;

const_iterator begin() const;
const_iterator end() const;

static bool less(const FastSet& leftSet, const FastSet& rightSet);
static bool equal(const FastSet& leftSet, const FastSet& rightSet);

public:
struct sortedAppender
{
// STL iterator preconditions
typedef std:utput_iterator_tag iterator_category;
typedef BASE value_type;
typedef ptrdiff_t difference_type;
typedef BASE* pointer;
typedef BASE& reference;

sortedAppender(FastSet& fastSet): m_fastSet(fastSet) {}

sortedAppender& operator=(value_type v) { m_fastSet.sortedAppend(v); return *this;}
sortedAppender& operator*() { return *this; }
sortedAppender& operator++() { return *this; }
sortedAppender& operator++(int) { return *this; }

FastSet& m_fastSet;
};

private:
SetType m_set;
};

} // end of namespace RX

To me the error message suggests that SortedAppender is not a valid output iterator. Specifically, it is not assignable as required by the standard. Also, it is very odd design to return the object itself from operator* rather a proxy or a reference to a member should be returned. In your case the iterator acts as value_type proxy as well. That is poor design.

Anyway, you will probably need to implement operator=( const SortedAppender&) and for that to work you'll probably have to make the m_fastSet a pointer as a reference can't rebind.

edit: Oh, I didn't bother to look carefully enough, but when you use a pointer for m_fastSet the compiler can generate the copy-assignment operator for you with the appropriate semantics.

-hg