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require 'rails/initializable'
require 'rails/configuration'
module Rails
# Railtie is the core of the Rails Framework and provides all the hooks and
# methods you need to link your plugin into Rails.
#
# What Railtie does is make every component of Rails a "plugin" and creates
# an API that exposes all the powers that the builtin components need
# to any plugin author.
#
# In fact, every major component of Rails (Action Mailer, Action Controller,
# Action View, Active Record and Active Resource) are all now just plain
# old plugins, so anything they can do, your plugin can do.
#
# Developing a plugin for Rails does not _require_ any implementation of
# Railtie, there is no fixed rule, but as a guideline, if your plugin works
# by just being required before Rails boots, then there is no need for you
# to hook into Railtie, but if you need to interact with the Rails framework
# during boot, or after boot, then Railtie is what you need to do that
# interaction.
#
# For example, the following would need you to implement Railtie in your
# plugin:
#
# * creating initializers (including route insertion)
# * modifying the render path (think HAML et al)
# * adding Rails config.* keys to the environment
# * setting up a subscriber to the Rails +ActiveSupport::Notifications+
# * adding global Rake tasks into rails
# * setting up a default configuration for the Application
#
# Railtie gives you a central place to connect into the Rails framework. If you
# find yourself writing plugin code that is having to monkey patch parts of the
# Rails framework to achieve something, there is probably a better, more elegant
# way to do it through Railtie, if there isn't, then you have found a lacking
# feature of Railtie, please lodge a ticket.
#
# Implementing Railtie in your plugin is by creating a class Railtie in your
# application that has your plugin name and making sure that this gets loaded
# durng boot time of the Rails stack.
#
# You can do this however you wish, but three straight forward ways are:
#
# == For gems or plugins that are not used outside of Rails
#
# * Create a Railtie subclass within your lib/my_plugin.rb file:
#
# # lib/my_plugin.rb
# module MyPlugin
# class Railtie < Rails::Railtie
# end
# end
#
# * Pass in your plugin name
#
# # lib/my_plugin.rb
# module MyPlugin
# class Railtie < Rails::Railtie
# plugin_name :my_plugin
# end
# end
#
# == For gems that could be used without Rails
#
# * Create a file (say, lib/my_gem/railtie.rb) which contains class Railtie inheriting from
# Rails::Railtie and is namespaced to your gem:
#
# # lib/my_gem/railtie.rb
# module MyGem
# class Railtie < Rails::Railtie
# end
# end
#
# * Require your own gem as well as rails in this file:
#
# # lib/my_gem/railtie.rb
# require 'my_gem'
# require 'rails'
#
# module MyGem
# class Railtie < Rails::Railtie
# end
# end
#
# * Give your gem a unique name:
#
# # lib/my_gem/railtie.rb
# require 'my_gem'
# require 'rails'
#
# module MyGem
# class Railtie < Rails::Railtie
# plugin_name :my_gem
# end
# end
#
# * Make sure your Gem loads the railtie.rb file if Rails is loaded first, an easy
# way to check is by checking for the Rails constant which will exist if Rails
# has started:
#
# # lib/my_gem.rb
# module MyGem
# require 'lib/railtie' if defined?(Rails)
# end
#
# * Or instead of doing the require automatically, you can ask your users to require
# it for you in their Gemfile:
#
# # #{USER_RAILS_ROOT}/Gemfile
# gem "my_gem", :require_as => ["my_gem", "my_gem/railtie"]
#
class Railtie
autoload :Configurable, "rails/railtie/configurable"
autoload :Configuration, "rails/railtie/configuration"
include Initializable
ABSTRACT_RAILTIES = %w(Rails::Plugin Rails::Engine Rails::Application)
class << self
def subclasses
@subclasses ||= []
end
def inherited(base)
unless abstract_railtie?(base)
base.send(:include, self::Configurable)
subclasses << base
end
end
def railtie_name(railtie_name = nil)
@railtie_name ||= name.demodulize.underscore
@railtie_name = railtie_name if railtie_name
@railtie_name
end
def railtie_names
subclasses.map { |p| p.railtie_name }
end
def subscriber(subscriber)
Rails::Subscriber.add(railtie_name, subscriber)
end
def rake_tasks(&blk)
@rake_tasks ||= []
@rake_tasks << blk if blk
@rake_tasks
end
def generators(&blk)
@generators ||= []
@generators << blk if blk
@generators
end
protected
def abstract_railtie?(base)
ABSTRACT_RAILTIES.include?(base.name)
end
end
def rake_tasks
self.class.rake_tasks
end
def generators
self.class.generators
end
def load_tasks
rake_tasks.each { |blk| blk.call }
end
def load_generators
generators.each { |blk| blk.call }
end
end
end
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