Dealing with crazy nested hashes in MailChimp API responses

mailing_list.rb

require "delegate"
require "singleton"

module MailingList
  class SafeResponse < SimpleDelegator
    def self.safe_delegate(*methods)
      methods.each do |method|
        define_method(method, ->(*args, &block) {
          value = __getobj__.send(method, *args, &block)
          value ? SafeResponse.new(value) : BlackHole.instance
        })
      end
    end

    safe_delegate :[]
    safe_delegate :detect, :find, :first, :select
  end

  class BlackHole
    include Singleton

    def itself; self end # TODO remove when upgrading to Ruby 2.2+
    [:detect, :find, :first, :select].each do |method|
      alias_method method, :itself
    end
    def [](*); self end

    def empty?; true end
    alias_method :blank?, :empty?
    def presence; nil end
    def present?; false end
  end
end

response = MailingList::SafeResponse.new(foo: [{bar: true}, {baz: false}])
response[:foo].first[:bar].presence # => true
response[:foo].first[:baz].presence # => nil
response[:nonsense].find { |x| false }.first["asdf"][0].present? # => false