Class: Hashie::Dash

### Home Classes Methods

### In Files

- lib/hashie/dash.rb

### Parent

Hashie::Hash

### Methods

- ::inherited
- ::new
- ::property
- ::property?
- ::required?
- #[]
- #[]=
- #_regular_reader
- #_regular_writer

### Included Modules

- Hashie::PrettyInspect

### Class/Module Index

Quicksearch

- Hashie
- Hashie::Clash
- Hashie::Clash::ChainError
- Hashie::Dash
- Hashie::Hash
- Hashie::HashExtensions
- Hashie::Mash
- Hashie::PrettyInspect
- Hashie::Trash

No matching classes.

# 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]
properties[R]
required_properties[R]

### Public Class Methods

inherited(klass) click to toggle source

    # File lib/hashie/dash.rb, line 67
    def self.inherited(klass)
      super
      (@subclasses ||= Set.new) << klass
      klass.instance_variable_set('@properties', self.properties.dup)
      klass.instance_variable_set('@defaults', self.defaults.dup)
      klass.instance_variable_set('@required_properties', self.required_properties.dup)
    end

new(attributes = {}, &block) click to toggle source

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

    # File lib/hashie/dash.rb, line 89
    def initialize(attributes = {}, &block)
      super(&block)

      self.class.defaults.each_pair do |prop, value|
        self[prop] = value
      end

      attributes.each_pair do |att, value|
        self[att] = value
      end if attributes
      assert_required_properties_set!
    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.

    # File lib/hashie/dash.rb, line 30
    def self.property(property_name, options = {})
      property_name = property_name.to_sym

      self.properties << property_name

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

      unless instance_methods.map { |m| m.to_s }.include?("#{property_name}=")
        class_eval           def #{property_name}(&block)            self.[](#{property_name.to_s.inspect}, &block)          end          def #{property_name}=(value)            self.[]=(#{property_name.to_s.inspect}, value)          end
      end

      if defined? @subclasses
        @subclasses.each { |klass| klass.property(property_name, options) }
      end
      required_properties << property_name if options.delete(:required)
    end

property?(name) click to toggle source

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

    # File lib/hashie/dash.rb, line 77
    def self.property?(name)
      properties.include? name.to_sym
    end

required?(name) click to toggle source

Check to see if the specified property is required.

    # File lib/hashie/dash.rb, line 83
    def self.required?(name)
      required_properties.include? name.to_sym
    end

### Public Instance Methods

[](property) click to toggle source

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

    # File lib/hashie/dash.rb, line 108
    def [](property)
      assert_property_exists! property
      value = super(property.to_s)
      yield value if block_given?
      value
    end

Also aliased as: _regular_reader
[]=(property, value) click to toggle source

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

    # File lib/hashie/dash.rb, line 117
    def []=(property, value)
      assert_property_required! property, value
      assert_property_exists! property
      super(property.to_s, value)
    end

Also aliased as: _regular_writer
_regular_reader(property) click to toggle source
Alias for: []
_regular_writer(property, value) click to toggle source
Alias for: []=

[Validate]

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