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.inherited(klass)

def self.inherited(klass)
  super
  (@subclasses ||= Set.new) << klass
  klass.instance_variable_set('@properties', properties.dup)
  klass.instance_variable_set('@defaults', defaults.dup)
  klass.instance_variable_set('@required_properties', required_properties.dup)
end

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

existing Dash.
property, to raise an error if a value is unset in a new or
* :required - Specify the value as required for this

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
  if options.key?(:default)
    defaults[property_name] = options[:default]
  elsif defaults.key?(property_name)
    defaults.delete property_name
  end
  unless instance_methods.map { |m| m.to_s }.include?("#{property_name}=")
    define_method(property_name) { |&block| self.[](property_name.to_s, &block) }
    property_assignment = property_name.to_s.concat('=').to_sym
    define_method(property_assignment) { |value| self.[]=(property_name.to_s, value) }
  end
  if defined? @subclasses
    @subclasses.each { |klass| klass.property(property_name, options) }
  end
  required_properties << property_name if options.delete(:required)
end

def self.property?(name)

defined.
Check to see if the specified property has already been

def self.property?(name)
  properties.include? name.to_sym
end

def self.required?(name)

required.
Check to see if the specified property is

def self.required?(name)
  required_properties.include? name.to_sym
end

def [](property)

property's default value if it hasn't been set).
Retrieve a value from the Dash (will return the

def [](property)
  assert_property_exists! property
  value = super(property.to_s)
  # If the value is a lambda, proc, or whatever answers to call, eval the thing!
  if value.is_a? Proc
    self[property] = value.call # Set the result of the call as a value
  else
    yield value if block_given?
    value
  end
end

def []=(property, value)

on pre-existing properties.
Set a value on the Dash in a Hash-like way. Only works

def []=(property, value)
  assert_property_required! property, value
  assert_property_exists! property
  super(property.to_s, value)
end

def assert_property_exists!(property)

def assert_property_exists!(property)
  unless self.class.property?(property)
    fail NoMethodError, "The property '#{property}' is not defined for this Dash."
  end
end

def assert_property_required!(property, value)

def assert_property_required!(property, value)
  if self.class.required?(property) && value.nil?
    fail ArgumentError, "The property '#{property}' is required for this Dash."
  end
end

def assert_property_set!(property)

def assert_property_set!(property)
  if send(property).nil?
    fail ArgumentError, "The property '#{property}' is required for this Dash."
  end
end

def assert_required_properties_set!

def assert_required_properties_set!
  self.class.required_properties.each do |required_property|
    assert_property_set!(required_property)
  end
end

def initialize(attributes = {}, &block)

just like you would many other kinds of data objects.
You may initialize a Dash with an attributes hash

def initialize(attributes = {}, &block)
  super(&block)
  self.class.defaults.each_pair do |prop, value|
    self[prop] = begin
      value.dup
    rescue TypeError
      value
    end
  end
  initialize_attributes(attributes)
  assert_required_properties_set!
end

def initialize_attributes(attributes)

def initialize_attributes(attributes)
  attributes.each_pair do |att, value|
    self[att] = value
  end if attributes
end

def merge(other_hash)

def merge(other_hash)
  new_dash = dup
  other_hash.each do |k, v|
    new_dash[k] = block_given? ? yield(k, self[k], v) : v
  end
  new_dash
end

def merge!(other_hash)

def merge!(other_hash)
  other_hash.each do |k, v|
    self[k] = block_given? ? yield(k, self[k], v) : v
  end
  self
end

def replace(other_hash)

def replace(other_hash)
  other_hash = self.class.defaults.merge(other_hash)
  (keys - other_hash.keys).each { |key| delete(key) }
  other_hash.each { |key, value| self[key] = value }
  self
end

Modules

Classes