I think a good way to learn ranges is by looking at the interface to them, compared to those used by other languages. For one thing, C++ iterators are way more complicated than what you will find in many other languages; for example Java's iterator interface[1] is similar to a D range[2].
In both languages the interface is 3 functions (there are many types of ranges which require more, but only one kind of iterator). Java: bool hasNext() E next() void remove() D: bool empty() E front() void popFront() These look almost identical but the semantics are very different. For example, hasNext() requires a look-ahead, while empty() does not. This is important since you may not be able to look ahead in a range. next() performs the equivalent of calling front(); popFront(); And remove() has nothing to do with the iterator as it performs on the underlining collection. Removing the look-ahead is probably one of the biggest improvements over Java's iterator. 1. http://java.sun.com/j2se/1.5.0/docs/api/java/util/Iterator.html 2. http://digitalmars.com/d/2.0/phobos/std_range.html#isInputRange clueless bystander Wrote: > Watching D evolve from the outside there seems to be a lot of ongoing > discussion > on this newsgroup about the D range idiom which is somehow opposed to > conventional > thinking about iterators. > > Can someone please explain in plain words just exactly what a range is and how > it differs from the iterator concept (if that's appropriate???) and what are > the benefits > from a data modeling and access perspective. > > Sure, I'm clueless, though suspect many other bystanders would appreciate a > succinct heads-up. > > Thanks, > clueless bystander
