From: Tomoyuki Kosimizu <greentea@...2.so-net.ne.jp>
Date: 2003-11-27T09:42:02+09:00
Subject: Re: Range does not take an Range object.

I am happy that there were at least three persons (included me) who
implemented Range#include? or intersect? incorrectly in the
world. And, interestingly, each person implement them in different
way.

It seems valuable that include? and intersect? are built-in.

greentea2fa2.so-net.ne.jp

class Range
  alias_method :original_include?, :include?

  def include?(other)
    return original_include?(other) unless other.is_a?(Range)
    return other.first >= first && other.last <= last
  end

  def intersect?(other)
    return true if include?(other)
    return include?(other.last) || include?(other.first) || other.include?(first) || other.include?(last)
  end
end