Problem with inheritance and classes in Ruby

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I have this code. I cannot print the editor variable in the incrementNameTitle method, it is not being displayed. The result is as follows:

Publisher: In Flames - Collins!

class Editora 
   attr_accessor :nameEditora
   def initialize(nameEditora)
      @nameEditora = nameEditora
   end
   def incrementNameTitle
      puts "Editora #{@nameEditora}: #{@title} - #{@author}!"
   end
end
   
class Book < Editora
   attr_accessor :title, :author
   def initialize(title, author)
      @title = title
      @author = author
   end
end

book = Book.new("Em Chamas", "Collins")
editora = Editora.new('LucasLivros')

puts book.incrementNameTitle
ruby

  • You urged the classes separately, so why use inheritance? A book is a publishing house?

  • Um, I’m learning POO so I didn’t get your comment right. How can I access the variables title and Author in the Book class?

  • Inheritance should be used to create subtypes, or a specialization of an abstraction. In doing Book inherit from Editora You’re basically defining a book as a subtype of a publishing house. That doesn’t make sense. Perhaps what would make more sense there is composition - and who knows you can read more deeply about it.

  • Okay! Thank you very much!

  • How could I manage to access the name of the publisher next to the name and author of the book?

1 answer

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As Woss commented in his question, you are making an inheritance, when in fact, what you need here is a composition.

You can change the book builder to receive a publisher:

class Book
   # code omitted...
   def initialize(title, author, editora)
     # code omitted...

After that, you define the method incrementNameTitle in Book, as now you are to receive the publisher in the builder, you will have access to what you want.

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