shared_from_this called from constructor

Question

I have to register an object in a container upon its creation. Without smart pointers I\'d use something like this:

a_class::a_class()
{
    register_somewhere(t         


        

Answer 1

There is no need for shared_ptr in your code (as you show it and explain it). A shared_ptr is only appropriate for shared ownership.

Your b_class doesn't own it's a_class, in fact is even outlived by it, so it should merely keep an observing pointer.

If b_class is polymorphic and the manipulations of a_class involve altering its b_class pointer, you should use a unique_ptr:

class a_class;
class b_class
{
  friend class a_class;
  a_class* mya;
  b_class(a_class*p)
  : mya(p) {}
public:
  virtual~b_class() {}   // required for unique_ptr to work
  virtual void fiddle(); // do something to mya
};

class a_class
{
  std::unique_ptr myb;
public:
  a_class()
  : myb(new b_class(this)) {}
  template
  void change_myb()
  {
    myb.reset(new B(this));
  }
};