Class: Wahashie::Dash

Inherits:
Hash
  • Object
show all
Includes:
PrettyInspect
Defined in:
lib/wahashie/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

included, #wahashie_inspect

Methods inherited from Hash

#to_hash, #to_json

Methods included from HashExtensions

included, #to_mash, #wahashie_stringify_keys, #wahashie_stringify_keys!

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/wahashie/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

Class Attribute Details

.defaults ⇒ Object (readonly)

Returns the value of attribute defaults.



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# File 'lib/wahashie/dash.rb', line 60

def defaults
  @defaults
end

.properties ⇒ Object (readonly)

Returns the value of attribute properties.



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# File 'lib/wahashie/dash.rb', line 60

def properties
  @properties
end

.required_properties ⇒ Object (readonly)

Returns the value of attribute required_properties.



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# File 'lib/wahashie/dash.rb', line 61

def required_properties
  @required_properties
end

Class Method Details

.inherited(klass) ⇒ Object 



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# File 'lib/wahashie/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

.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.

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



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# File 'lib/wahashie/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)\n        self.[](\#{property_name.to_s.inspect}, &block)\n      end\n\n      def \#{property_name}=(value)\n        self.[]=(\#{property_name.to_s.inspect}, value)\n      end\n    ACCESSORS\n  end\n\n  if defined? @subclasses\n    @subclasses.each { |klass| klass.property(property_name, options) }\n  end\n  required_properties << property_name if options.delete(:required)\nend\n"

.property?(name) ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/wahashie/dash.rb', line 77

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

.required?(name) ⇒ Boolean

Check to see if the specified property is required.

Returns:

  • (Boolean) 


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# File 'lib/wahashie/dash.rb', line 83

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

Instance Method Details

#[](property) {|value| ... } ⇒ Object

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

Yields:

  • (value) 


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# File 'lib/wahashie/dash.rb', line 108

def [](property)
  assert_property_exists! property
  value = super(property.to_s)
  yield value if block_given?
  value
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/wahashie/dash.rb', line 117

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