Sort Example

# sort by example

class Counter 
  def initialize
    @count = 0
  end

  def inc
    @count += 1
  end

  def count
    @count
  end
end

counter = Counter.new

class Apple
  attr_reader :id

  def initialize(id, counter)
    @id = id
    @counter = counter
  end

  def value
    @counter.inc
    [id % 3, id]
  end

  def <=>(other)
    value <=> other.value
  end
end

apples = 100.times.map { |id| Apple.new(id, counter) }; nil

apples.sort

puts counter.count
# => 1224