ruby should I use self. or @

Question

Here is my ruby code

class Demo
  attr_accessor :lines

  def initialize(lines)
    self.lines = lines
  end
end

In the above code I could have

Answer 1

I think there is a little difference that has not be mentioned yet. The instance variable @lines can only be accessed within the class.

class Foo
 def initialize
   @lines = 1
 end
end

foo = Foo.new
foo.lines
>> NoMethodError: undefined method `lines' for #
foo.send(:lines)
>> 1

If you define attr_accessor :lines all instances of that class can access the lines variable:

class Foo
 attr_accessor :lines
 def initialize
   self.lines = 1
 end
end

foo = Foo.new
foo.lines
>> 1

If you want your variable to be accessible for all instances you should use attr_accessor.