App Class

app.rb

class Environment
  def self.values
    %w(debug development test staging production)
  end

  values.each do |env|
    class_eval %Q{
      def #{env}?
        @env == :#{env}
      end
    }
  end

  def initialize
    env = ENV.fetch('ENV', 'development').downcase.to_sym

    fail 'Unknown env setting' unless self.class.values.include?(env.to_s)

    @env = env.to_sym
  end

  def to_s
    @env.to_s
  end

  def to_sym
    @env.to_sym
  end
end

class App
  @@env = Environment.new

  def self.version
    '1.13.0'
  end

  def self.env
    @@env
  end
end

class Environment
  extend Forwardable

  VALID_ENVS = %i(debug development test staging production).freeze

  def_delegators :@env, :to_s, :to_sym

  def initialize
    @env = ENV.fetch('ENV', 'development').downcase.to_sym
    fail 'Unknown env setting' unless VALID_ENVS.include?(@env)
  end

  VALID_ENVS.each do |env|
    define_method("#{env}?") { @env == env }
  end
end

class App
  VERSION = '1.13.0'.freeze

  def self.version
    VERSION
  end

  def self.env
    @env ||= Environment.new
  end
end