Don't use self, unless it is required.

gistfile1.rb

# Only use self when it is necessary.
# reader methods do not require self unless a local variable is declared with the same name (which is a bad idea anyway)
# setter methods do require self, otherwise you are creating a local variable

# Minimal use of self (only writes use 'self')
class Person
 
  attr_accessor :name, :date_of_birth
  
  def initialize(name:, date_of_birth:)
    self.name = name
    self.date_of_birth = date_of_birth
  end
  
  def greet
    puts "Hi, my name is #{name}"
  end
  
  def age
    Time.now.year - date_of_birth.year
  end
  
end

# Unnessary use of self (read and writes both are prefaced with 'self')
class Person
 
  attr_accessor :name, :date_of_birth
  
  def initialize(name:, date_of_birth:)
    self.name = name
    self.date_of_birth = date_of_birth
  end
  
  def greet
    puts "Hi, my name is #{self.name}"
  end
  
  def age
    Time.now.year - self.date_of_birth.year
  end
  
end