class Hashie::Dash

A Dash is a 'defined' or 'discrete' Hash, that is, a Hash that has a set of defined keys that are accessible (with optional defaults) and only those keys may be set or read.

Dashes are useful when you need to create a very simple lightweight data object that needs even fewer options and resources than something like a DataMapper resource.

It is preferrable to a Struct because of the in-class API for defining properties as well as per-property defaults.

Attributes

defaults[R]
getters[R]
properties[R]
required_properties[R]

Public Class Methods

inherited(klass) click to toggle source
Calls superclass method
# File lib/hashie/dash.rb, line 69
def self.inherited(klass)
  super
  (@subclasses ||= Set.new) << klass
  klass.instance_variable_set('@properties', properties.dup)
  klass.instance_variable_set('@getters', getters.dup)
  klass.instance_variable_set('@defaults', defaults.dup)
  klass.instance_variable_set('@required_properties', required_properties.dup)
end
property(property_name, options = {}) click to toggle source

Defines a property on the Dash. Options are as follows:

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

  • :required - Specify the value as required for this property, to raise an error if a value is unset in a new or existing Dash. If a Proc is provided, it will be run in the context of the Dash instance. If a Symbol is provided, the property it represents must not be nil. The property is only required if the value is truthy.

  • :message - Specify custom error message for required property

# File lib/hashie/dash.rb, line 36
def self.property(property_name, options = {})
  properties << property_name

  if options.key?(:default)
    defaults[property_name] = options[:default]
  elsif defaults.key?(property_name)
    defaults.delete property_name
  end

  define_getter_for(property_name)
  define_setter_for(property_name)

  @subclasses.each { |klass| klass.property(property_name, options) } if defined? @subclasses

  condition = options.delete(:required)
  if condition
    message = options.delete(:message) || "is required for #{name}."
    required_properties[property_name] = { condition: condition, message: message }
  elsif options.key?(:message)
    raise ArgumentError, 'The :message option should be used with :required option.'
  end
end
property?(name) click to toggle source

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

# File lib/hashie/dash.rb, line 80
def self.property?(name)
  properties.include? name
end
required?(name) click to toggle source

Check to see if the specified property is required.

# File lib/hashie/dash.rb, line 86
def self.required?(name)
  required_properties.key? name
end