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.

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 = {}) ⇒ Dash

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



76
77
78
79
80
81
82
83
84
 
# File 'lib/hashie/dash.rb', line 76

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

Class Method Details

.defaults ⇒ Object

The default values that have been set for this Dash



63
64
65
66
67
68
69
70
71
72
 
# File 'lib/hashie/dash.rb', line 63

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

.properties ⇒ Object

Get a String array of the currently defined properties on this Dash.



45
46
47
48
49
50
51
52
53
54
 
# File 'lib/hashie/dash.rb', line 45

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

.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.



26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
 
# File 'lib/hashie/dash.rb', line 26

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

.property?(prop) ⇒ Boolean

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

Returns:

  • (Boolean) 


58
59
60
 
# File 'lib/hashie/dash.rb', line 58

def self.property?(prop)
  properties.include?(prop.to_s)
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).



88
89
90
 
# File 'lib/hashie/dash.rb', line 88

def [](property)
  super(property.to_sym) if property_exists? property
end

#[]=(property, value) ⇒ Object

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



94
95
96
 
# File 'lib/hashie/dash.rb', line 94

def []=(property, value)
  super if property_exists? property
end