Metafunction as member function parameter

Question

Currently my code has this form:

template <typename T>
class A {
private:
  T data;
public:
  void apply_process(A<T> obj, std::function<T(A<T>&)> process) {
    data = process(obj);
  }
  // ... 
};

This works with runtime lambdas; yet, while obj will be only known on runtime,process will be known at compile time. Can I rewrite this somehow so that process is a metafunction to be passed as a compile-time parameter? A C++14 solution is preferable.

Answer 1

It is not clear what you want, but by combining up the keywords you are throwing, I think you want this:

template <typename T>
class A {
private:
  T data;
public:
  template<class UnaryFunction>
  void apply_process(A<T> obj, UnaryFunction process) {
    data = process(obj);
  }
  // ... 
};

to be a bit more pedantic use perfect forwarding (from comment):

  void apply_process(A<T> obj, UnaryFunction&& process) {
    data = std::forward<UnaryFunction>(process)(obj);
  }