From: Kyle Hunter <lists@...>
Date: 2013-07-03T11:39:08+09:00
Subject: Implementing sort/sort!

Hello,

I was wondering about implementing sort/sort!. Basically, I have a Point
class, which contains x, y variables of a 2d Cartesian point. It also
includes the Comparable mixin and thus implements a <=> method.

I also have a Polygon class which is really just a container for an
array of the aforementioned Point class. I guess the name is a misnomer
but I'm working on adding functionality. Anyway, I want Polygon.sort to
return a new Polygon with the points sorted, and Polygon.sort! to modify
the points inside of the current polygon.

I've attempted it, and it seems to work, but I was wondering if anyone
could recommend a more canonical or idiomatic way to do it, or point out
any flaws with my approach.

class Point
  include Comparable
  attr_accessor :x, :y

  def initialize(x, y)
    @x = x
    @y = y
  end

  def <=>(other)
    x_cmp = @x <=> other.x
    x_cmp != 0 ? x_cmp : @y <=> other.y
  end
end

class Polygon
  include Enumerable
  attr_accessor :points
  alias_method :_sort, :sort

  def initialize(points)
    @points = points
  end

  def each(&blk)
    @points.each(&blk)
  end

  def sort
    Polygon.new _sort
  end

  def sort!
    @points = _sort
  end
end

# Example usage
poly = Polygon.new [Point.new(3,4), Point.new(1,2)]
poly.sort
poly.sort!

-- 
Posted via http://www.ruby-forum.com/.