Discussion on: Ruby Getters and Setters

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Another neat trick is you can mark these as private so you can use them internally without worrying about them leaking out by throwing a private into the class.

This can be useful if you don't like remembering when to use @year vs year or perhaps you want to be prepared to abstract it later.

require "date"
class Movie
  attr_accessor :name, :year
  private :year, :year=

  def initialize(name, year)
    @name = name
    @year = year
  end

  def age
    Date.today.year - year
  end
end
obj1 = Movie.new("Forrest Gump", 1994)
obj1.year #=> NoMethodError: private method `year' called for #<Movie:....>
obj1.year = 2018 #=> NoMethodError: private method `year=' called for #<Movie:....>
obj1.age #=> 24

K-Sato • Nov 15 '18 • Edited

Thanks for sharing !!

Scott Tadman • Nov 15 '18

It seems odd to declare these as private since you can always refer to them by their @ name internally.

Philip Hallstrom • Nov 15 '18

It can be odd, but it can also be useful as it allows you to more easily override it later without having to go find/replace all instances of @year in your class.

Or, if a class inherits from it and needs to change how year is generated it's easier it doesn't have to worry about parent class using @year.

If that makes sense.

Scott Tadman • Nov 15 '18

It just seems inconsistent to use year and self.year = ... in the code where one's bare and the other's necessarily prefixed, instead of @year consistently. This plus the way that @year is by default "private".

One of the major goals of object-oriented design is to properly contain any changes like that, so replacing @year with something else is at least contained to the one file or scope.

Subclass concerns are valid, though in Ruby it's generally understood you need to play nice with your parent's properties and avoid really getting in there and wrecking around.