polymorphic C++ references

Question

I was wondering how you can do polymorphism with references, as opposed to pointers.

To clarify, see the following minimal example:

cl         


        

Answer 1

I realize this is a really old post but there is another option you have for handling references for dynamically allocated objects. You can assign a reference to the dynamically allocated object. Below is some dummy code to give you an idea of how this works.

struct A
{
  int b;
  virtual void print();
  A(int val):b(val) {}
};

struct A_child:public A
{
  A_child(int val):A(val) {}
  void print();
};

void A:print()
{
cout<<"parent\n";
}

void A_child:print()
{
cout<<"child\n";
}

struct test_ref
{
A *& ref;
test_ref(A * ptr) : ref(ptr)
}

int main()
{

  test_ref parent(new A(12));
  parent.ref->print();

  test_ref child(new A_child(15));
  child.ref->print();
} 

To be honest I am not certain when this is a good idea. I just wanted to show an alternative approach where you dont have to dereference the dynamically allocated memory when initializing an object.

I am also pretty certain dynamically allocating a pointer while initializing a class where the pointer is stored as a reference pointer will probably lead to a memory leak unless you can delete the reference pointer.