Advanced OOP Lesson

app.rb

require 'byebug'

require_relative 'boat'
require_relative 'canoe'
require_relative 'motorboat'
require_relative 'sailboat'

puts "------------ Advanced OOP: Gone Fishin' ------------"

canoe = Canoe.new('Voyager', 16, 3, 1.25)
puts canoe.description

# p canoe.water_volume_displacement # Error private method `water_volume_displacement' called
# you cannot call private methods from outside the class

motorboat = Motorboat.new('Usain Boat', 38, 10, 3.23)
puts motorboat.description

sailboat = Sailboat.new('Black Pearl', 150, 30, 15)
puts sailboat.description
puts "------------"


puts sailboat.skipper? # public interface instance method
sailboat.skipper = "Jack Sparrow" # NoMethodError
puts sailboat.skipper?
puts "The #{sailboat.name}'s skipper is Captain #{sailboat.skipper}"

# puts motorboat.skipper?
# cannot call method defined in inherited sibling classes

puts "------------"


puts "The follow are types of sailboats:"
puts Sailboat.types.join(", ") # class method

# cannot call class method on the instance!!!
p sailboat.types # NotMethodError

boat.rb

class Boat
  # Class Constant:
  SEAWATER_WEIGHT_PER_CUBIC_FOOT = 64.1

  # Getter
  attr_reader :name # creates a name public interface

  # runs on .new instanciation: Canoe.new
  def initialize(name, length, width, depth)
    # instance variable with an initial value
    @name = name
    @length = length
    @width = width
    @depth = depth
  end

  # Public Interface (can be called from the outside world):
  def displacement
    (water_volume_displacement * SEAWATER_WEIGHT_PER_CUBIC_FOOT).round
  end

  def description
    # in instance methods...
    # self references/refers to the (specific) instance
    "The #{self.name} is a #{self.class.to_s.downcase}. "\
    "It has a displacement of #{self.displacement} pounds."
  end
  # Public Interface ends here

  # Private method below:
  private

  def water_volume_displacement
    @length * @width * @depth
  end
end

butler.rb

class Butler
  # Butler.new(house) => instance of House
  def initialize(house)
    # in order to create a butler
    # we need an instance of House
    @house = house # We want @house to store an instance of House
  end

  def clean_house
    # @house is an instance of House
    puts "#{@house.name} cleaned!"
  end
end

canoe.rb

class Canoe < Boat
end


# ThisIsUpperCamelCase # => class / modules names
# this_is_snake_case # =>  variables, methods and filenames

house.rb

class House
  attr_reader :name, :butler

  def initialize(name)
    @name = name
    # assign an instance of Buttler
    # to the house that is being created
    @butler = Butler.new(self) # We need to pass the current instance of House
  end
end

motorboat.rb

class Motorboat < Boat
end

sailboat.rb

class Sailboat < Boat
  # attr_writer :skipper
  # attr_reader :skipper
  attr_accessor :skipper # creates both a reader and a writter

  # Defines a Class method
  # self here refers to the Class itself
  def self.types # Sailboat.types
    # self refers to the Sailboat class
    %w[Cutter Dinghy Galleon Sloop Schooch]
  end

  def skipper? # instance method
    # self refers to the instance on which
    # the method skipper? was called
    # @skipper != nil
    [email protected]?
  end

  # Setter
  # def skipper=(skipper)
  #   @skipper = skipper
  # end

  # Getter
  # def skipper
  #   @skipper
  # end

  private

  def water_volume_displacement
    # super - run the parent code (method)
    # boat.water_volume_displacement
    super + 500
  end
end