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copied!<p>You can't cast <code>_1</code> to <code>T</code> (at the time of the bind expression). </p> <p>You need a lazy cast. Perhaps define a function and use a nested bind expression, or use Boost Phoenix with a custom <code>any_cast</code> actor.</p> <p>Here's the nested bind approach:</p> <pre><code>#include <boost/any.hpp> #include <boost/function.hpp> #include <boost/bind.hpp> #include <boost/lambda/lambda.hpp> #include <boost/unordered_map.hpp> struct type_info_hash { std::size_t operator()(std::type_info const & t) const { return 42; // t.hash_code(); } }; struct equal_ref { template <typename T> bool operator()(boost::reference_wrapper<T> a,boost::reference_wrapper<T> b) const { return a.get() == b.get(); } }; struct any_visitor { boost::unordered_map<boost::reference_wrapper<std::type_info const>, boost::function<void(boost::any&)>, type_info_hash, equal_ref> fs; template <typename T> static T any_cast_f(boost::any& any) { return boost::any_cast<T>(any); } template <typename T> void insert_visitor(boost::function<void(T)> f) { try { fs.insert(std::make_pair(boost::ref(typeid(T)), boost::bind(f, boost::bind(any_cast_f<T>, boost::lambda::_1)))); } catch (boost::bad_any_cast& e) { std::cout << e.what() << std::endl; } } bool operator()(boost::any & x) { boost::unordered_map<boost::reference_wrapper<std::type_info const>, boost::function<void(boost::any&)>, type_info_hash, equal_ref>::iterator it = fs.find(boost::ref(x.type())); if (it != fs.end()) { it->second(x); return true; } else { return false; } } }; struct abc {}; void fa(int i) { std::cout << "fa(" << i << ")" << std::endl; } void fb(abc) { std::cout << "fb(abc())" << std::endl; } int main() { any_visitor f; f.insert_visitor<int>(fa); f.insert_visitor<abc>(fb); std::vector<boost::any> xs; xs.push_back(1); xs.push_back(abc()); xs.push_back(1.5); for (auto it=xs.begin(); it!=xs.end(); ++it) if (!f(*it)) std::cout << "no visitor registered" << std::endl; } </code></pre> <p>Prints output:</p> <pre><code>fa(1) fb(abc()) no visitor registered </code></pre>

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