organge_tree.rb

# This is how you define your own custom exception classes

class NoOrangesError < StandardError
end
 
class DeadTreeError < StandardError
end
 
class OrangeTree
  attr_reader :age, :height, :oranges
  def initialize(age = 0, height = 0)
    @age = age
    @height = height
    @oranges = []
  end  
  # Ages the tree one year
  def age!
    @oranges = []
    return "This tree is dead!" if dead?
    increment_age
    increment_height
    grow_oranges
  end
 
  # Returns +true+ if there are any oranges on the tree, +false+ otherwise
  def any_oranges?
    @oranges.size > 0
  end
 
  def dead?
    @age >= 100
  end
 
  # Returns an Orange if there are any
  # Raises a NoOrangesError otherwise
  def pick_an_orange!
    raise NoOrangesError, "This tree has no oranges" unless self.any_oranges?
    raise DeadTreeError, "This tree is dead" if self.dead?
    @oranges[0]
    @oranges.shift
  end
 
  private
 
  def grow_oranges
    rand(5..10).times {@oranges << Orange.new(rand(6..12))} if @age > 5
  end
 
  def increment_age
    @age += 1
  end
 
  def increment_height
    @height += 1 if @age < 25
  end
 
end
 
class Orange
  attr_reader :diameter
 
  def initialize(diameter)
    @diameter = diameter
  end
end
 
tree = OrangeTree.new
 
tree.age! until tree.any_oranges?
 
puts "Tree is #{tree.age} years old and #{tree.height} feet tall"
 
until tree.dead?
  basket = []
 
  # It places the oranges in the basket
  while tree.any_oranges?
    basket << tree.pick_an_orange!
  end
  
  total_diameter = 0
  basket.each {|orange| total_diameter += orange.diameter}
  avg_diameter = total_diameter / basket.size
 
  puts "Year #{tree.age} Report"
  puts "Tree height: #{tree.height} feet"
  puts "Harvest:     #{basket.size} oranges with an average diameter of #{avg_diameter} centimeters."
  puts ""
 
  # Age the tree another year
  tree.age!
end
 
puts "Alas, the tree, she is dead!"