Decltype for return of a function

Question

I am making a templated class that is a wrapper around any iterator. I am making the operator* this way:

template 
class MyIterator {
public:
          


        

Answer 1

This is what std::declval is for:

decltype(*std::declval<T>()) operator*() { /* ... */ }

If your implementation does not provide std::declval (Visual C++ 2010 does not include it), you can easily write it yourself:

template <typename T>
typename std::add_rvalue_reference<T>::type declval(); // no definition required

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Since T is an iterator type, you could also use the std::iterator_traits template, which does not require any C++0x support:

typename std::iterator_traits<T>::reference operator*() { /* ... */ }