has_own_find.h

#include <type_traits>
#include <utility>
#include <algorithm>


namespace has_own_find_impl__ {
    struct two__ { char c__[2]; };

    template <class T> static two__ test__(...);
    template <class T> static char test__(decltype(std::declval<T>().find(std::declval<typename T::key_type>()))* = 0);
}

namespace {
    template <class T>
    struct has_own_find
        : public std::integral_constant<bool, sizeof(has_own_find_impl__::test__<T>(nullptr)) == sizeof(char)>
    {};

    template<class Cont, class T>
    auto do_find(const Cont& c, T&& value) -> typename std::enable_if<!has_own_find<Cont>::value, typename Cont::const_iterator>::type
    {
        using std::begin;
        using std::end;

        return std::find(begin(c), end(c), std::forward<T>(value));
    }

    template<class Cont, class T>
    auto do_find(const Cont& c, T&& value) -> typename std::enable_if<has_own_find<Cont>::value, typename Cont::const_iterator>::type
    {
        return c.find(std::forward<T>(value));
    }
}

//////////////////////////////////////////////////////////////
// Usage example:
template<class Cont>
void do_it()
{
    const Cont c{1,2,3,4,5};

    auto const it = do_find(c, 2);
    assert(it != c.end());
    
    std::cout << *it << "\n";
}

do_it<std::vector<int>>();
do_it<std::set<int>>();
//////////////////////////////////////////////////////////////

why do u use forward()?