Ruby Self

The keyword self in ruby gives you access to the current object

Class

In the context of a class self refers to the current class

class Dog
  p self # the Dog class
end

Defining a method on self creates a class method

Instance Method

Within an instance method self refers to the instance itself

class Dog
  def bark
    self
  end
end

p Dog.new.bark # an instance of the Dog class

Implicit Self
When you call a method without an explicit recieving object, the method is called implicitely on self. In plain english this means that if there is nothing on the left hand side of the function call then the left hand side is self.

class Person
  attr_reader :first_name, :last_name

  def initialize(first_name, last_name)
    @first_name = first_name
    @last_name = last_name
  end

  def full_name
    "#{first_name} #{last_name}" #implied self. Instance of person
  end
end