class Hashie::Dash

def initialize(attributes = {})

just like you would many other kinds of data objects.
You may initialize a Dash with an attributes hash 
def initialize(attributes = {})
  self.class.properties.each do |prop|
    self.send("#{prop}=", self.class.defaults[prop.to_sym])
  end
  attributes.each_pair do |att, value|
    self.send("#{att}=", value)
  end
end