A class to keep a short, persistent history of some values.

history.rb

require 'csv'

class History
  def initialize(name, cols, size) 
		@f=name
		@headers=cols
		@size=size
		read
		write
	end

	def read
		@csv=[]
		if File.exists?(@f)
			CSV.foreach(@f, {:headers => :first_row, :converters => [:numeric]}) do |row|

				@csv << row
			end
		end
		@csv=@csv.last(@size)
	end

	def write
		@csv=@csv.last(@size)
		CSV.open(@f, 'w') do |out|
			out << @headers
			@csv.each{|row| out << row}
		end
	end

	def << (row)
		@csv << row
		write
	end

	private :read, :write


end

History.new('hist.csv', ['x','y'], 5) << [rand(),rand()]