Make a hash with keys callable as methods

deep_struct.rb

class DeepStruct
  attr_reader :hash

  def initialize(hash)
    @hash = hash.with_indifferent_access
  end

  def method_missing(method, *args, &block)
    if hash.key?(method)
      value = hash[method]
      if value.kind_of? Hash
        self.class.new(value)
      else
        value
      end
    else
      super
    end
  end

end

deep_struct_spec.rb

require_relative "deep_struct"
require "active_support/hash_with_indifferent_access"
require "active_support/core_ext/hash/indifferent_access"

describe DeepStruct do

  context "with string keys" do
    let(:hash) do
      DeepStruct.new({"a" => 1, "b" => 2, "c" => {"d" => 3}})
    end

    it "access keys directly" do
      hash.b.should eq(2)
    end

    it "access nested keys" do
      hash.c.d.should eq(3)
    end

  end

  context "with symbol keys" do
    let(:hash) do
      DeepStruct.new({a: 1, b: 2, c: {d: 3}})
    end

    it "access keys directly" do
      hash.b.should eq(2)
    end

    it "access nested keys" do
      hash.c.d.should eq(3)
    end

  end

end