From: Akinori MUSHA <redmine@...>
Date: 2008-12-12T19:32:44+09:00
Subject: [ruby-core:20499] [Feature #709](Rejected) Enumerator#+

Issue #709 has been updated by Akinori MUSHA.

Status changed from Open to Rejected
Assigned to changed from Yukihiro Matsumoto to Akinori MUSHA

To tell the truth, I was also tempted to add something like that and
you are not alone.

You might as well add:

class Enumerator
  alias * cycle

  def -@
    Enumerator.new { |y| to_a.reverse_each { |i| y << i } }
  end
end

and have fun with them as follows:

e = -[1,4,7].each * 3 + ("a".."c").each
p e.to_a #=> [3, 2, 1, 3, 2, 1, 3, 2, 1, "a", "b", "c"]

However, I am yet to think that even the addition of enumerators is so
commonly in need.

Besides, as you said, operators must be carefully chosen and defined so
that they work consistently and systematically and they look intuitive
and practical, all at the same time.  We should also think how other
types of iterators should be introduced, such as bidirectional iterators
and indexable iterators, before defining a variety of operators for
the current Enumerator.

So, my answer here, for now, is the block based enumerator.  Just as you
have aptly shown, you can define anything you like with it without the
need for predefined operators.
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