class Hashie::Dash

API for defining properties as well as per-property defaults.
It is preferrable to a Struct because of the in-class
resources than something like a DataMapper resource.
lightweight data object that needs even fewer options and
Dashes are useful when you need to create a very simple
optional defaults) and only those keys may be set or read.
that has a set of defined keys that are accessible (with
A Dash is a ‘defined’ or ‘discrete’ Hash, that is, a Hash

def self.defaults

The default values that have been set for this Dash 
def self.defaults
  properties = {}
  ancestors.each do |elder|
    if elder.instance_variable_defined?("@defaults")
      properties.merge! elder.instance_variable_get("@defaults")
    end
  end
  
  properties
end

def self.properties

properties on this Dash.
Get a String array of the currently defined 
def self.properties
  properties = []
  ancestors.each do |elder| 
    if elder.instance_variable_defined?("@properties")
      properties << elder.instance_variable_get("@properties")
    end
  end
  properties.flatten.map{|p| p.to_s}
end

def self.property(property_name, options = {})


Dash.
to be returned before a value is set on the property in a new
* :default - Specify a default value for this property,

as follows:
Defines a property on the Dash. Options are 
def self.property(property_name, options = {})
  property_name = property_name.to_sym
  (@properties ||= []) << property_name
  (@defaults ||= {})[property_name] = options.delete(:default)
  class_eval <<-RUBY
    def #{property_name}
      self[:#{property_name}]
    end
    def #{property_name}=(val)
      self[:#{property_name}] = val
    end
  RUBY
end

def self.property?(prop)

defined.
Check to see if the specified property has already been 
def self.property?(prop)
  properties.include?(prop.to_s)
end

def [](property)

property's default value if it hasn't been set).
Retrieve a value from the Dash (will return the 
def [](property)
  super(property.to_sym) if property_exists? property
end

def []=(property, value)

on pre-existing properties.
Set a value on the Dash in a Hash-like way. Only works 
def []=(property, value)
  super if property_exists? property
end

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

def property_exists?(property)


Raises an NoMethodError if the property doesn't exist 
def property_exists?(property)
  unless self.class.property?(property.to_sym)
    raise NoMethodError, "The property '#{property}' is not defined for this Dash."
  end
  true
end