Class: Feature::ConstantLookup

Inherits:
Object
  • Object
show all
Defined in:
lib/toggles/constant_lookup.rb

Constant Summary collapse

Error = 
Class.new(NameError) do
  attr_reader :sym

  def initialize(sym)
    @sym = sym
    super(sym.join('::'))
  end
end

Class Method Summary collapse

Class Method Details

.from(features, path) ⇒ Object

Return a tree walker that translates Module#const_missing(sym) into the next child node

So Features::Cat::BearDog walks as:

  • next_features = Feature.features # root

  • const_missing(:Cat) => next_features = next_features

  • const_missing(:BearDog) => next_features

  • const_missing(:CN22) => next_features

Defined at Toggles.features_dir + “/cat/bear_dog.yaml”

Raises:

  • (Error) —

    if constant cannot be resolved



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# File 'lib/toggles/constant_lookup.rb', line 22

def self.from(features, path)
  Class.new {
    class << self
      attr_accessor :features, :path

      def const_missing(sym)
        # translate class name into path part i.e :BearDog #=> 'bear_dog'
        key = sym.to_s
        key.gsub!(/([A-Z\d]+)([A-Z][a-z])/, '\1_\2'.freeze)
        key.gsub!(/([a-z\d])([A-Z])/, '\1_\2'.freeze)
        key.downcase!

        subtree_or_feature = features.fetch(key.to_sym)

        if subtree_or_feature.is_a?(Hash)
          Feature::ConstantLookup.from(subtree_or_feature, path + [sym])
        else
          subtree_or_feature
        end
      rescue KeyError
        raise Error, path + [sym]
      end
    end
  }.tap do |resolver|
    resolver.features = features
    resolver.path = path
  end
end