Using a std::unordered_set of std::unique_ptr

Question

Assume I have a set of unique_ptr:

std::unordered_set > my_set;

I\'m not sure what\'s the safe way to

Answer 1

You can also use a deleter that optionally doesn't do anything.

template
struct maybe_deleter{
  bool _delete;
  explicit maybe_deleter(bool doit = true) : _delete(doit){}

  void operator()(T* p) const{
    if(_delete) delete p;
  }
};

template
using set_unique_ptr = std::unique_ptr>;

template
set_unique_ptr make_find_ptr(T* raw){
    return set_unique_ptr(raw, maybe_deleter(false));
}

// ...

int* raw = new int(42);
std::unordered_set> myset;
myset.insert(set_unique_ptr(raw));

auto it = myset.find(make_find_ptr(raw));

Live example.