Class: Hashie::Dash

Inherits:
Hash
  • Object
show all
Includes:
PrettyInspect
Defined in:
lib/hashie/dash.rb

Overview

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.

Direct Known Subclasses

Trash

Class Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from PrettyInspect

#hashie_inspect, included

Methods inherited from Hash

#to_hash, #to_json

Methods included from HashExtensions

#hashie_stringify_keys, #hashie_stringify_keys!, included, #to_mash

Constructor Details

#initialize(attributes = {}, &block) ⇒ Dash

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



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# File 'lib/hashie/dash.rb', line 73

def initialize(attributes = {}, &block)
  super(&block)

  self.class.defaults.each_pair do |prop, value|
    self.send("#{prop}=", value)
  end

  attributes.each_pair do |att, value|
    self.send("#{att}=", value)
  end if attributes
end

Class Attribute Details

.defaults ⇒ Object (readonly)

Returns the value of attribute defaults.



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# File 'lib/hashie/dash.rb', line 53

def defaults
  @defaults
end

.properties ⇒ Object (readonly)

Returns the value of attribute properties.



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# File 'lib/hashie/dash.rb', line 53

def properties
  @properties
end

Class Method Details

.inherited(klass) ⇒ Object 



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# File 'lib/hashie/dash.rb', line 58

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)
end

.property(property_name, options = {}) ⇒ Object

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.



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# File 'lib/hashie/dash.rb', line 26

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

  self.properties << property_name

  if options[:default] or self.defaults[property_name]
    self.defaults[property_name] = options[:default] 
  end

  unless instance_methods.map { |m| m.to_s }.include?("#{property_name}=")
    class_eval <<-ACCESSORS
      def #{property_name}
        _regular_reader(#{property_name.to_s.inspect})
      end

      def #{property_name}=(value)
        _regular_writer(#{property_name.to_s.inspect}, value)
      end
    ACCESSORS
  end

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

.property?(name) ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/hashie/dash.rb', line 67

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

Instance Method Details

#[](property) ⇒ Object

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



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# File 'lib/hashie/dash.rb', line 91

def [](property)
  assert_property_exists! property
  super(property.to_s)
end

#[]=(property, value) ⇒ Object

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



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# File 'lib/hashie/dash.rb', line 98

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