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POTemplate functor error in g++
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  1. POTemplate functor error in g++
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    copied!<p>I've got some code where I would like to build a vector of elements using the mapped values in a map. The code below works fine in Visual Studio (and seems legit as far as I can tell), but g++ disagrees.</p> <pre><code>template&lt;class PAIR&gt; typename PAIR::second_type foo(const PAIR&amp; arg) { return (arg.second); } class A { private: typedef std::map&lt;int, std::wstring&gt; map_t; map_t m_map; public: void bar() { // Attempt to pulled the mapped type from the map into the vector std::vector&lt;std::wstring&gt;vect(m_map.size()); std::transform(m_map.begin(), m_map.end(), vect.begin(), &amp;foo&lt;map_t::value_type&gt;); // &lt;-- error here, see below, also // other attempts that all failed: // - std::transform(..., boost::bind(foo&lt;map_t::value_type&gt;, _1)); // - std::transform(..., boost::bind(&amp;map_t::value_type::second, _1)); // - also tried casting foo to a specific function type // - also tried "template&lt;class T&gt; T itself(T arg) { return T; }" applied to all the above functor candidates, a la "std::transform(..., itself(&lt;&lt;functor&gt;&gt;));" } }; </code></pre> <p>Unfortunately, I don't have the exact error text with me (something about not being able to figure out which overloaded function to use) at the moment or the specific version of g++ (the latest being distributed with Ubuntu), but I'll update this post when I get that.</p> <p>In the meantime, can anyone explain why g++ can't resolve the type of the functor being provided?</p>
 

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