Additional arguments for custom deleter of shared_ptr

Question

Is there anyway I can send arguments to the deleter of std::shared_ptr?

something that would feel like:

std::shared_ptr<A> myA( a, myDeleter(a, 5) );   

where myDeleter has this signature:

void myDeleter(A* a, int i)

(Obviously the syntax above is wrong, but just to emphasize that I need my deleter to take extra arguments.)

Answer 1

You could std::bind your deleter's second argument before passing it as the deleter:

auto deleter = std::bind(myDeleter, std::placeholders::_1, 5);
std::shared_ptr<A> myA(a, deleter);

Alternatively, your deleter could be a functor that takes the int through its constructor:

struct myDeleter
{
  myDeleter(int);
  void operator()(A*);
};

myDeleter deleter(5);
std::shared_ptr<A> myA(a, deleter);

Alternatively you could use a lambda expression:

std::shared_ptr<A> myA(a, [](A* a){ myDeleter(a, 5); });