Reference Wrappers

A reference wrapper is a copy-constructible and copy-assignable wrapper for a object of type&, which is defined in the header <functional>. So you have an object, that behaves like a reference, but can be copied. In opposite to classic references, std::reference_wrapper objects support two additional use cases:

• You can use them in containers of the Standard Template Library. std::vector<std::reference_wrapper<int>> myIntRefVector
• You can copy instances of classes, which have std::reference_wrapper objects. That is in general not possible with references.

To access the reference of a std::reference_wrapper<int> myInt(1), the get method can be used: myInt.get(). You can use a reference wrapper to encapsulate and invoke a callable.

Reference wrappers

// referenceWrapperCallable.cpp 
...
#include <functional>
...
void foo(){ 
  std::cout << "Invoked" << std::endl; 
}

typedef void callableUnit();
std...