From: Yui NARUSE <naruse@...>
Date: 2011-10-04T16:46:44+09:00
Subject: [ruby-core:39916] [Ruby 1.9 - Feature #5389] New method Enumerator#iterate


Issue #5389 has been updated by Yui NARUSE.


Enumerator#next is not enough?
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Feature #5389: New method Enumerator#iterate
http://redmine.ruby-lang.org/issues/5389

Author: Joey Zhou
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


If we want to iterate over the elements of a enumerable object with *multiple* blocks, we can use the Enumerator class.

A method 'iterate' is required, we can write it in Ruby:

    class Enumerator
      def iterate
        yield_value = self.next
        return_value = yield yield_value
        self.feed return_value
        self
      end
    end

Well, here is an example:

    array = (1..10).to_a
    enum = array.map!

    loop do
      enum.iterate {|n| n + 10 }
      enum.iterate {|n| n * 2 }
      enum.iterate {|n| -n }
    end

    p array # => [11, 4, -3, 14, 10, -6, 17, 16, -9, 20]

We want to map an array: the 1st element use blk1, the 2nd use blk2, the 3rd use blk3...

I think this Enumerator#iterate method is sometimes useful, so would you please introduce it into the language core?



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