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POstd::async variant which works over a collection
 

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  1. POstd::async variant which works over a collection
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    <p>Using <code>std::async</code> I was wondering whether it is possible to have a helper function, which creates <code>std::future</code>s from a collection (one future for every collection element).</p> <p>Often I have the following situation:</p> <pre><code>auto func = []( decltype(collection)::reference value ) { //Some async work }; typedef std::result_of&lt;decltype(func)&gt;::type ResultType; std::vector&lt;std::future&lt;ResultType&gt;&gt; futures; futures.reserve(collection.size()); // Create all futures for( auto&amp; element : collection ) { futures.push_back(std::async(func, element)); } // Wait till futures are done for( auto&amp; future : futures ) { future.wait(); } </code></pre> <p>To be able to easily reuse this I came up with the following partial code:</p> <pre><code>template&lt; class Function, class CT, class... Args&gt; std::vector&lt;std::future&lt;typename std::result_of&lt;Function(Args...)&gt;::type&gt;&gt; async_all( Function&amp;&amp; f, CT&amp; col ) { typedef typename std::result_of&lt;Function(Args...)&gt;::type ResultType; std::vector&lt;std::future&lt;ResultType&gt;&gt; futures; futures.reserve(collection.size()); for( auto&amp; element : collection ) { futures.push_back(std::async(func, element)); } } return futures; </code></pre> <p>Now I have to solve the <code>Args</code> problem, since in <code>async_all</code>, <code>Args</code> cannot be deduced anymore. The only thing I currently can think of is another functor, which converts an element in collection to <code>Args</code>. Is there any more elegant solution to this?</p>
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