From: duerst@...
Date: 2016-06-07T06:18:18+00:00
Subject: [ruby-dev:49647] [Ruby trunk Feature#4787] Integer#each_modulo(n)

Issue #4787 has been updated by Martin Dürst.


This only gives the 'mod' part. Why not extend this to get both the 'div' part and the 'mod' part back (see also comment #4)?

And why not allow an array of integers as an argument? Some conventions for displaying large numbers with separators are not uniform, in particular in India (see https://en.wikipedia.org/wiki/Indian_numbering_system).

----------------------------------------
Feature #4787: Integer#each_modulo(n)
https://bugs.ruby-lang.org/issues/4787#change-59042

* Author: Kenta Murata
* Status: Assigned
* Priority: Normal
* Assignee: Yukihiro Matsumoto
----------------------------------------
I suggest a new feature of Integer to enumerate by iterated Integer#modulo.
An example implementation in Ruby is the following code:

```ruby
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:

```ruby
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.


---Files--------------------------------
each_modulo.patch (3.91 KB)


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