Question

class BookInStock      

  attr_reader   :isbn
  attr_accessor :price

  def initialize(isbn, price)
    @isbn  = isbn
    @price = Float(price)
  end    

  def price_in_cents
    Integer(price*100 + 0.5) # why can they use price here? why are they not using @price?
  end

  def price_in_cents=(cents)
    @price = cents / 100.0
  end
  # ...
end

book = BookInStock.new("isbn1", 33.80)
puts "Price          = #{book.price}"
puts "Price in cents = #{book.price_in_cents}"
book.price_in_cents = 1234
puts "Price          = #{book.price}"
puts "Price in cents = #{book.price_in_cents}"

Answer 1

Because attr_accessor creates a getter.

That’s why you can write book.price later, too.

Kind of inconsistent on their part, though.