Extended STL, Volume 1: Collections and Iterators

Chapter 35. Intermezzo: Proscribing Fatuous Output Iterator Syntax Using the Dereference Proxy Pattern

	If knowledge can create problems, it is not through ignorance that we can solve them.
	--Isaac Asimov

As was discussed in the last chapter, std::ostream_iterator supports the required semantics of an output iterator by using a simple implementation trick, whereby the dereference operator (operator *()) returns an instance to the object and an assignment operator (operator =()) taking the assigned type is defined. (See Listing 34.5 to see how it is implemented for stlsoft::ostream_iterator.) Consider the following code:

1  std::ostream_iterator<int>  iter(std::cout);
2
3  *iter = 10;  // Sensible

Line 3 is equivalent to:

iter.operator *().operator =(10); ...