about when_any Function (C++ REST SDK)

Question

here https://msdn.microsoft.com/en-us/library/jj969480.aspx

the code is like this

template<typename _Iterator>
auto when_any(_Iterator _Begin, _Iterator _End, const task_options& _TaskOptions = task_options())
-> decltype (details::_WhenAnyImpl<typename std::iterator_traits<_Iterator>::value_type::result_type, _Iterator>::_Perform(_TaskOptions, _Begin, _End))
{
       typedef typename std::iterator_traits<_Iterator>::value_type::result_type _ElementType;
       return details::_WhenAnyImpl<_ElementType, _Iterator>::_Perform(_TaskOptions, _Begin, _End);
}

my question is

 typedef typename std::iterator_traits<_Iterator>::value_type::result_type _ElementType;

where is result_type coming from?

thanks a lot

[See the Casablanca docs **here**](http://microsoft.github.io/cpprestsdk/classpplx_1_1task.html). — WhozCraig, May 12 '16 at 08:34
so, it seems std::iterator_traits<_Iterator>::value_type should be task, — apple dragon, May 12 '16 at 08:44

score 1 · Answer 1 · edited May 16 '16 at 08:58

1

I solved the problem.

Looks like std::iterator_traits<_Iterator>::value_type should be correct.

edited May 16 '16 at 08:58

Box Box Box Box

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answered May 12 '16 at 08:46

apple dragon

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@graham.reeds: Actually, he's putting the answer he found as an answer, which is _absolutely the correct thing to do_. (He hasn't done it very well, though.) **Answers do not go in the comments section.** – Lightness Races in Orbit May 12 '16 at 09:24
@graham.reeds I just reframed the wording of the answer and now it is an answer. – Box Box Box Box May 16 '16 at 09:00

about when_any Function (C++ REST SDK)

1 Answers1