[RUBY] In order not to confuse the understanding of getters and setters, [Do not use accessors for anything! ]

There are several getter and setter commentary articles, so I'll leave that to you. Also, there is a convenient code called Accessor, but I didn't have enough information about how to use it properly, so I wrote it as a basis for beginners.

First of all, it is a place to design a common car.

If you can use accessors

Car design

class Car
  attr_accessor :model, :color, :option
  def initialize(model, color, option)
    @model = model
    @color = color
    @option = option
  end
end

car = Car.new("Benz", "white", "wheel")

#=>All can be changed

If this is the case, you can put it together with attr_accessor, For example, ** "I'm already making a car, but I'm in trouble if I can change the color with the car model !!! (I wish it was only an option ...)" **

When using getters and setters

Car design

class Car
  attr_reader :model, :color, :option
  attr_writer :option 
  def initialize(model, color, option)
    @model = model
    @color = color
    @option = option
  end
end

car = Car.new("Benz", "white", "wheel")

#=>Only options can be changed

It's common to write that, If you want to write smarter with accessors

Smart to use accessors and getters

Car design

class Car
  attr_accessor :option
  attr_reader :model, :color 
  def initialize(model, color, option)
    @model = model
    @color = color
    @option = option
  end
end

car = Car.new("Benz", "white", "wheel")

#=>Only options can be changed

Will be.

By the way,

When I try to change the model of the car ...

Car design

class Car
  attr_accessor :option
  attr_reader :model, :color 
  def initialize(model, color, option)
    @model = model
    @color = color
    @option = option
  end
end

car = Car.new("Benz", "white", "wheel")

car.model = "BMW"
#=>NoMethodError (undefined method `model=' for #<Car:0x00007fc009900440>)

I get angry like that! !! ** "Don't change the car model! I'm already making it!" ** That's right. Attempting to change the color will result in a similar error.

Summary

So, I looked back on how to use getters, setters, and accessors for Ruby beginners to study. I hope it will be helpful for beginners. Thank you very much! !!