From: ahoward <ahoward@...>
Date: 2002-11-15T05:40:58+09:00
Subject: Array#next - Enumerable#next ?



rubyists-

does anyone know a way to implement this generically for all enumerable
objects in an efficient manner?

  class Array
    def next
      # start iterating if we never have before
      @itr = 0 unless @itr
      @itr = @itr.succ

      # if there are no more elements return nil
      # but also set itr back to zero so subsequent
      # calls to next will succeed
      if @itr > size
	@itr = 0
	return nil
      end

      return self[@itr - 1]
    end
  end

this is really usefull.  if it could be done for any Enumerable object then
something like this :

  module Kernel
    def concert(*enumerables, &block)
      args = enumerable.collect{|e| e.next}
      return if args.include? nil
      block.call *args
    end
  end


  h = {:answer => 42}
  a = [42]

  concert(h, a) do |k,v,a|
    puts k, v, a
  end


would be *very* cool.  also, this could be more generic than some of the
methods being suggested for things like this...

-a



-- 

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 | Ara Howard
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