Vital Ruby Lab 5

presentation.rb

class Array
  def sum
    inject(0.0) { |result, el| result + el }
  end

  def mean
    sum / size
  end
end

class InvalidScoreError < RuntimeError
end

class Presentation
  attr_accessor :presentation_id, :title, :presenter, :subject, :scores

  def initialize(presentation_id, title, presenter, subject)
    @presentation_id, @title, @presenter, @subject = [presentation_id, title, presenter, subject]
    @scores = []
  end

  def self.parse(line)
    self.new(*line.split(':'))
  end

  def add_score(score)
    raise InvalidScoreError if !score.is_a?(Integer) || score < 1 || score > 5
    @scores << score
  end

  def average_score
    return @scores.mean unless @scores.empty?
    0.0
  end
end

read_only_proxy.rb

$: << File.dirname(__FILE__)
require 'presentation'

class ReadOnlyProxy
  def initialize(target)
    @target = target
  end

  def method_missing(sym, *args, &block)
    if sym.to_s !~ /=$/
      @target.send(sym, *args, &block)
    endx
  end
end

p = Presentation.new("1", "Talking to Whales", "Phinehas Phisch", "oceanography")
ro = ReadOnlyProxy.new(p)

puts ro.title
ro.title = "HACKED"
puts ro.title