The following code example is taken from the book
C++ Templates - The Complete Guide
by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
© Copyright David Vandevoorde and Nicolai M. Josuttis 2002
template <typename T>
class Holder {
private:
T* ptr; // refers to the object it holds (if any)
public:
// default constructor: let the holder refer to nothing
Holder() : ptr(0) {
}
// constructor for a pointer: let the holder refer to where the pointer refers
explicit Holder (T* p) : ptr(p) {
}
// destructor: releases the object to which it refers (if any)
~Holder() {
delete ptr;
}
// assignment of new pointer
Holder<T>& operator= (T* p) {
delete ptr;
ptr = p;
return *this;
}
// pointer operators
T& operator* () const {
return *ptr;
}
T* operator-> () const {
return ptr;
}
// get referenced object (if any)
T* get() const {
return ptr;
}
// release ownership of referenced object
void release() {
ptr = 0;
}
// exchange ownership with other holder
void exchange_with (Holder<T>& h) {
std::swap(ptr,h.ptr);
}
// exchange ownership with other pointer
void exchange_with (T*& p) {
std::swap(ptr,p);
}
private:
// no copying and copy assignment allowed
Holder (Holder<T> const&);
Holder<T>& operator= (Holder<T> const&);
};