What is attr_accessor in Ruby?

Question

I’m learning Ruby on Rails and in the content I am studying I could not understand well what is the attr_accessor and how it works.

Answer 1

The attr_accessor is a "shortcut" that creates read, write and instance variable methods in a class.

http://apidock.com/ruby/Module/attr_accessor

Ex.:

Suppose you have a class Carro wanted to access a property cor:

class Carro
end

carro = Carro.new
carro.cor # => NoMethodError: undefined method `cor'
carro.cor = 'azul' # => NoMethodError: private method `cor='

You could implement it this way:

class Carro
   @cor=nil

   def cor
      @cor
   end

   def cor=(value)
     @cor = value
   end

end

In this way,

carro = Carro.new
carro.cor = 'azul'
carro.cor # => "azul"

Using attr_accessor, this code is created for you, the class would look like this:

class Carro
   attr_accessor :cor
end

and the functionality is the same.