Alphonse Cuccurullo2,513 Points
A bit confused on classes. attr reader and writer?
"""""""""""""So just a few questions to get me on the right path with classes. The attr_reader and writers. I have noticed that its a way to rewrite over certain functions in a class but in this video it is used in a different way. Like the accessor holds vaiables or symbols i'm guessing but there being used in a way similar to how we use instance variables in a initialize method. So just wondering whats going on there."""""""""
""""""""""Also i have noticed certain videos that have classes without a initialize method. Can someone give me a point is to why this initialize method is necessary and in what situations? Is it only to have a constructor? if so that is the constructor of importance?""""""""""
Ilya Dolgirev35,374 Points
Hi! Regarding classes - all your custom classes inherit from Object class if you don't define your own inheritance instead. You can check it in IRB:
class Person end Person.superclass # => Object
Therefore, if you didn't define your custom initializer, Ruby will lookup to superclass `initialize' method (Object in this case) and will invoke that one - it just creates a blank instance without any instance variables. But If you need to initialize some variables when creating instance of your class you have to define your own initializer.
About attributes methods - it just a handy way(aka 'syntax sugar') to defining methods for getting or setting the values of instance variables. These classes below are identical but look at amount of code we need to write in second case.
# USING SYNTAX SUGAR class Person attr_reader :name attr_accessor :hobbies def initialize(name) @name = name end end # NOT USING SYNTAX SUGAR class Person def initialize(name) @name = name end # This is 'attr_reader' for 'name' instance variable under the hood def name @name end # And this is 'attr_accessor' for 'hobbies' instance variable under the hood def hobbies @hobbies end def hobbies=(value) @hobbies = value end end