class CookbookOmnifetch::Integration

def self.configurable(name)
  configurables << name
  attr_writer name
  define_method(name) do
    value = instance_variable_get("@#{name}".to_sym)
    case value
    when NullValue
      raise MissingConfiguration, "`#{name}` is not configured"
    when Proc
      value.call
    else
      value
    end
  end
end

def self.configurables
  @configurables ||= []
end

def initialize
  self.class.configurables.each do |configurable|
    instance_variable_set("@#{configurable}".to_sym, NullValue.new)
  end
end