[ruby-dev:43989] [Ruby 1.9 - Feature #4787] Integer#each_modulo(n)

[Yukihiro Matsumoto <matz@ruby-lang.org>]

Issue #4787 has been updated by Yukihiro Matsumoto.

Target version changed from 1.9.3 to 1.9.x


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Feature #4787: Integer#each_modulo(n)
http://redmine.ruby-lang.org/issues/4787

Author: Kenta Murata
Status: Open
Priority: Normal
Assignee: Yukihiro Matsumoto
Category: core
Target version: 1.9.x


I suggest a new feature of Integer to enumerate by iterated Integer#modulo.
An example implementation in Ruby is the following code:

  class Integer
    def each_modulo(n)
      raise ArgumentError, "argument must be an Integer" unless n.is_a? Integer
      raise ArgumentError, "argument must be larger than 1" if n <= 1
      return Enumerator.new(self, :each_modulo, n) unless block_given?
      q = self
      while q > 0
        q, r = q.divmod(n)
        yield(r)
      end
    end
  end
  
  p 133.each_modulo(3).to_a #=> [1, 2, 2, 1, 1]

The following code is an example use of the feature:

  class Integer
    def each_thousand_separation
      each_modulo(1000)
    end
  
    def thousand_separated_string(sep=',')
      each_thousand_separation.map(&'%03d'.method(:%)).inject{|s, n| n + sep + s }
    end
  end
  
  p 100_000_000_200.thousand_separated_string #=> "100,000,000,200"

I make an implementation in C, and attach the patch for that.


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