has_own_find.cpp

// inspired by https://gist.github.com/oliora/b8207b4a74a6bb868ef4
// a bit less text, less standard way

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

template <typename T>
constexpr bool has_own_find(...) { return false; }

template <typename T>
constexpr bool has_own_find(decltype(std::declval<T>().find(std::declval<typename T::key_type>()))* = 0) { return true; }

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

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


#include <vector>
#include <set>
int main(int argc, const char *argv[])
{
    std::vector<int> v;
    auto itv = do_find(v, 42);
    assert (itv == v.end());

    std::set<int> s;
    auto its = do_find(s, 42);
    assert (its == s.end());

    return 0;
}