From: Martin DeMello <martindemello@...>
Date: 2005-06-05T15:40:25+09:00
Subject: Re: internal iterators in ruby

Geert Fannes <Geert.Fannes@ikanconsulting.com> wrote:
> So, if I understand well, the problem with iterating over different
> enumerables synchronously has to do with the absence of a #rewind and
> #next method for enumerables. The Generator class solves this using the
> slow #callcc method and allows one to step through the Enumerable#each
> method, element by element. Wouldn't it be better if the enumerable
> required a #rewind and #next method and constructs the #each method out
> of these instead of doing the reverse using #callcc?

Note that an internal iterator is a (capable of being atomic) method,
whereas an external iterator is an *object* holding the state of the
iterator. If you want to implement #next, you need somewhere to store
@current, and the object you're iterating over is not that place.

martin