Requirements for a handle

We present in this chapter the concept of a handle to an object of type T. Basically a handle to an object of type T behaves as a pointer to an object of type T, except that it has no increment or decrement operators. A handle has two operators $*$ and $->$, which give access to the object pointed to.

Types

typedef T

value_type;

Creation

Handle<T> ht;
	ht references no object.
Handle<T> ht ( hr);
	copy constructor
Handle<T> ht ( T* pt);
	constructs a reference from a pointer T*.

Operations

Handle<T>&	ht = T* pr	ht points to the object *pr
Handle<T>&	ht = pr	ht and pr points to the same object.
void	ht.clear ()	sets ht to reference no object.

Dereference

T&	* ht	returns the object pointed to.
T*	ht ->	returns a pointer to the object pointed to.

Memory allocation

void

ht.Delete ()

deallocates the memory referenced by ht.

Equality

bool	ht.is_null ()	true if ht references no object.
bool	ht == hr	true if ht and q reference the same object.
bool	ht != hr	true if ht and hr reference distinct objects.