1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
require 'rails/initializable'
require 'rails/configuration'
require 'active_support/inflector'
require 'active_support/core_ext/module/introspection'
require 'active_support/core_ext/module/delegation'
module Rails
# Railtie is the core of the Rails framework and provides several hooks to extend
# Rails and/or modify the initialization process.
#
# Every major component of Rails (Action Mailer, Action Controller,
# Action View and Active Record) is a Railtie. Each of
# them is responsible for their own initialization. This makes Rails itself
# absent of any component hooks, allowing other components to be used in
# place of any of the Rails defaults.
#
# Developing a Rails extension does _not_ require any implementation of
# Railtie, but if you need to interact with the Rails framework during
# or after boot, then Railtie is needed.
#
# For example, an extension doing any of the following would require Railtie:
#
# * creating initializers
# * configuring a Rails framework for the application, like setting a generator
# * adding config.* keys to the environment
# * setting up a subscriber with ActiveSupport::Notifications
# * adding rake tasks
#
# == Creating your Railtie
#
# To extend Rails using Railtie, create a Railtie class which inherits
# from Rails::Railtie within your extension's namespace. This class must be
# loaded during the Rails boot process.
#
# The following example demonstrates an extension which can be used with or without Rails.
#
# # lib/my_gem/railtie.rb
# module MyGem
# class Railtie < Rails::Railtie
# end
# end
#
# # lib/my_gem.rb
# require 'my_gem/railtie' if defined?(Rails)
#
# == Initializers
#
# To add an initialization step from your Railtie to Rails boot process, you just need
# to create an initializer block:
#
# class MyRailtie < Rails::Railtie
# initializer "my_railtie.configure_rails_initialization" do
# # some initialization behavior
# end
# end
#
# If specified, the block can also receive the application object, in case you
# need to access some application specific configuration, like middleware:
#
# class MyRailtie < Rails::Railtie
# initializer "my_railtie.configure_rails_initialization" do |app|
# app.middleware.use MyRailtie::Middleware
# end
# end
#
# Finally, you can also pass :before and :after as option to initializer, in case
# you want to couple it with a specific step in the initialization process.
#
# == Configuration
#
# Inside the Railtie class, you can access a config object which contains configuration
# shared by all railties and the application:
#
# class MyRailtie < Rails::Railtie
# # Customize the ORM
# config.app_generators.orm :my_railtie_orm
#
# # Add a to_prepare block which is executed once in production
# # and before each request in development
# config.to_prepare do
# MyRailtie.setup!
# end
# end
#
# == Loading rake tasks and generators
#
# If your railtie has rake tasks, you can tell Rails to load them through the method
# rake_tasks:
#
# class MyRailtie < Rails::Railtie
# rake_tasks do
# load "path/to/my_railtie.tasks"
# end
# end
#
# By default, Rails load generators from your load path. However, if you want to place
# your generators at a different location, you can specify in your Railtie a block which
# will load them during normal generators lookup:
#
# class MyRailtie < Rails::Railtie
# generators do
# require "path/to/my_railtie_generator"
# end
# end
#
# == Application and Engine
#
# A Rails::Engine is nothing more than a Railtie with some initializers already set.
# And since Rails::Application is an engine, the same configuration described here
# can be used in both.
#
# Be sure to look at the documentation of those specific classes for more information.
#
class Railtie
autoload :Configurable, "rails/railtie/configurable"
autoload :Configuration, "rails/railtie/configuration"
include Initializable
ABSTRACT_RAILTIES = %w(Rails::Railtie Rails::Engine Rails::Application)
class << self
private :new
def subclasses
@subclasses ||= []
end
def inherited(base)
unless base.abstract_railtie?
base.send(:include, Railtie::Configurable)
subclasses << base
end
end
def rake_tasks(&blk)
@rake_tasks ||= []
@rake_tasks << blk if blk
@rake_tasks
end
def console(&blk)
@load_console ||= []
@load_console << blk if blk
@load_console
end
def generators(&blk)
@generators ||= []
@generators << blk if blk
@generators
end
def abstract_railtie?
ABSTRACT_RAILTIES.include?(name)
end
def railtie_name(name = nil)
@railtie_name = name.to_s if name
@railtie_name ||= generate_railtie_name(self.name)
end
protected
def generate_railtie_name(class_or_module)
ActiveSupport::Inflector.underscore(class_or_module).gsub("/", "_")
end
end
delegate :railtie_name, :to => "self.class"
def config
@config ||= Railtie::Configuration.new
end
def eager_load!
end
def load_console(app=self)
self.class.console.each { |block| block.call(app) }
end
def load_tasks(app=self)
extend Rake::DSL if defined? Rake::DSL
self.class.rake_tasks.each { |block| self.instance_exec(app, &block) }
# load also tasks from all superclasses
klass = self.class.superclass
while klass.respond_to?(:rake_tasks)
klass.rake_tasks.each { |t| self.instance_exec(app, &t) }
klass = klass.superclass
end
end
def load_generators(app=self)
self.class.generators.each { |block| block.call(app) }
end
def railtie_namespace
@railtie_namespace ||= self.class.parents.detect { |n| n.respond_to?(:railtie_namespace) }
end
end
end
|
