Own std::shared_ptr with std::make_shared

Question

For a debug situation I need to implement an own version of the shared_ptr class. Typical when I use std::shared_ptr I use a typedef for convenience:

typedef std::shared_ptr<myclass> myclassptr;

in a debug situation I want to extend the shared_ptr template, not the class myclass, with some additional debug methods instead of using the typedef:

class myclassptr : public std::shared_ptr<myclass>
{
  public:
   // some special tracking methodes
};

but that leave me with a cast at, which does not compile:

myclassptr mcp=std::make_shared<myclass>();

I already encapsulate the make_shared in a factory funktion like:

myclassptr createMyClass()
{
  return std::make_shared<myclass>();
}

but how can I get to my debug version?

Answer 1

Give myclassptr a constructor (and probably assignment operator too) which accepts a std::shared_ptr:

class myclassptr : public std::shared_ptr<myclass>
{
  public:
   // some special tracking methodes

    myclassptr(std::shared_ptr<myclass> arg)
      : std::shared_ptr<myclass>(std::move(arg))
    {}

    myclassptr& operator= (std::shared_ptr<myclass> src)
    {
      std::shared_ptr<myclass>::operator=(std::move(src));
      return *this;
    }
};

Depending on how you use myclassptr, you may or may not want to mark the constructor as explicit.