confusion about constructor

[targt123]

Here is a piece of code I found in a book:

template <class Comparable>
class BinarySearchTree 
{
  public:
  explicit BinarySearchTree ( cont Comparable & notFound);
  BinarySearchTree (const BinarySearchTree & rhs);
  BinarySearchTree <Comparable> (){root = NULL;}
  bool isEmpty() const { return root==NULL; }

  private:
  Node<Comparable> *root;
}

My question is why in the explicit constructor the argument is :
cont Comparable & notFound. I thought the argument should be type Node<Comparable> *root, since that is the private member. Thanks

[mzimmers]

"notFound" vs. "root" is just a placeholder name...doesn't mean anything.

Evidently, the constructor is passing the Comparable object by reference, rather than by address. If I remember correctly, this creates a copy of the object for the parameter.

[targt123]

But shouldn't the constructor argument be of type Node * and not Comparable &? The private member is of type Node not Comparable. Node itself is a class.

[mzimmers]

Can't say for sure without knowing what the constructor is doing, or for that matter, how the class is supposed to behave in general. But, it seems to be a valid copy constructor definition.