Question

how to make friend function of std::make_shared().

I tried:

class MyClass{
public:
     friend std::shared_ptr<MyClass> std::make_shared<MyClass>();
     //or
     //friend std::shared_ptr<MyClass> std::make_shared();
protected:
     MyClass();
};

but it does not work (i’am using Visual Studio 2010 SP1)

Answer 1

How about adding a static method to your class:

class Foo
{
public:
  static shared_ptr<Foo> create() { return std::shared_ptr<Foo>(new Foo); }
private:
  // ...
};

Here’s a little hackaround:

class Foo
{
  struct HideMe { };
  Foo() { };
public:
  explicit Foo(HideMe) { };
  static shared_ptr<Foo> create() { return std::make_shared<Foo>(HideMe());
};

Nobody can use the public constructor other than the class itself. It’s essentially a non-interface part of the public interface. Ask the Java people if such a thing has a name 🙂