Refactored Load Save Json Sketch (To isolate responsibilities and use Enumerable)

Here rather than sub-classing Array (which can be unsafe) we extend Enumerable, to make our BubbleData class iteratable (to do this, we only needed to provide the each method). But it also suited us to create a custom add method, so we can check whether the MAX_SIZE has been reached, and if so to "shift" the oldest bubble off the underlying array. We have also isolated OO responsibilities, in that the Sketch class only needs to know about the BubbleData class directly to "load", "display" and "add" bubbles.

# This example demonstrates how easily "sketch data" can be retrieved from a json file
# in ruby-processing. Note this sketch re-uses the Bubble class from the bubble library. 
# The BubbleData class, can load, store and create instances of Bubble (and request them
# to display and/or show their label, when 'mouse over').
# @author Martin Prout, after Daniel Shiffmans version for processing
# 
require "json"

load_library :bubble

attr_reader :bubble_data

def setup()
  size(640, 360)
  # initialize bubble_data with 'key' and read data from 'file path'
  @bubble_data = BubbleData.new "bubbles"
  bubble_data.load_data "data/data.json"
end

def draw
  background 255
  # draw the bubbles and display a bubbles label whilst mouse over
  bubble_data.display mouse_x, mouse_y
end

def mouse_pressed
  # create a new instance of bubble, where mouse was clicked
  bubble_data.create_new_bubble(mouse_x, mouse_y)
end

class BubbleData
  include Enumerable

  MAX_BUBBLE = 10

  attr_reader :key, :path, :bubbles

  # @param key String for top level hash

  def initialize key
    @key = key
    @bubbles = []
  end

  def each &block
    bubbles.each &block
  end

  def create_new_bubble x, y
    self.add Bubble.new(x, y, rand(40 .. 80), "new label")
    save_data
    load_data path
  end

  def display x, y
    self.each do |bubble|
      bubble.display
      bubble.rollover(x, y)
    end
  end

  # @param path to json file

  def load_data path
    @path = path
    source_string = open(path, "r"){ |file| file.read }
    data = JSON.parse(source_string)[key]
    bubbles.clear
    # iterate the bubble_data array, and create an array of bubbles
    data.each do |point|
      self.add Bubble.new(
        point["position"]["x"],
        point["position"]["y"],
        point["diameter"],
        point["label"])
    end
  end

  def add bubble
    bubbles << bubble
    bubbles.shift if bubbles.size > MAX_BUBBLE
  end

  private

  def save_data
    hash = { key => self.map{ |point| point.to_hash } }
    json = JSON.pretty_generate(hash)      # generate pretty output
    open(path, 'w') { |f| f.write(json) }
  end

end