Question

When accessing an instance variable via accessor method attribute, what is the difference between the expressions self.attribute and attribute? Say, we define an accessor:

def post
  @post
end

We can call

self.post

or simply

post

What is special about adding self?

Answer 1

It makes a difference when there might be a local var that shadows method call. Using self allows us to specify that we want the method, not the local var. See an example:

class Foo
  def post
    @post
  end

  def post= (content)
    @post = content
  end 

  def test
    #difference 1 
    p post # >> nil

    @post = 10
    p post # >> 10

    post = 42
    p post # >> 42
    p self.post # >> 10

    #difference 2
    # assign to @post, note that you can put space between "self.post" and "="
    self.post = 12 

    #otherwise it means assigning to a local variable called post.
    post = 12
  end
end

Foo.new.test