module Roda::RodaPlugins::Base::ClassMethods

def plugin(plugin, *args, &block)

Roda.plugin :csrf
Roda.plugin PluginModule

class has been subclassed, as doing so can break the subclasses.
Note that you should not load plugins into a Roda class after the

which will be required and then used. Returns nil.
which is used directly, or a symbol representing a registered plugin
Load a new plugin into the current class. A plugin can be a module 
def plugin(plugin, *args, &block)
  raise RodaError, "Cannot add a plugin to a frozen Roda class" if frozen?
  plugin = RodaPlugins.load_plugin(plugin) if plugin.is_a?(Symbol)
  raise RodaError, "Invalid plugin type: #{plugin.class.inspect}" unless plugin.is_a?(Module)
  if !plugin.respond_to?(:load_dependencies) && !plugin.respond_to?(:configure) && (!args.empty? || block)
    # RODA4: switch from warning to error
    RodaPlugins.warn("Plugin #{plugin} does not accept arguments or a block, but arguments or a block was passed when loading this. This will raise an error in Roda 4.")
  end
  plugin.load_dependencies(self, *args, &block) if plugin.respond_to?(:load_dependencies)
  include(plugin::InstanceMethods) if defined?(plugin::InstanceMethods)
  extend(plugin::ClassMethods) if defined?(plugin::ClassMethods)
  self::RodaRequest.send(:include, plugin::RequestMethods) if defined?(plugin::RequestMethods)
  self::RodaRequest.extend(plugin::RequestClassMethods) if defined?(plugin::RequestClassMethods)
  self::RodaResponse.send(:include, plugin::ResponseMethods) if defined?(plugin::ResponseMethods)
  self::RodaResponse.extend(plugin::ResponseClassMethods) if defined?(plugin::ResponseClassMethods)
  plugin.configure(self, *args, &block) if plugin.respond_to?(:configure)
  @app = nil
end