This document introduces a Namespace Less Engine that allows projects to reuse code from other projects without worrying about namespaces. Some key points: - It allows reusing an entire project (CMS, news system, etc.) rather than just parts of code. Everything can be inherited and overridden. - Models, controllers and other code can be written without namespaces. Placeholder files define inline namespaces. - Views cannot be directly inherited but can be overridden. Helpers can also be included. - The engine gem is included in the Gemfile. Migrations and other setup is installed via rake tasks. - Tips include using the engine as a submodule instead of gem, and generating models/controllers

1. Namespace Less Engine
reuse your projects should be a piece of cake!!
Shaokun Wu
shaokun.wu@gmail.com

2. What’s wrong with
Namespace

3. • Things like Devise are very very COOL!!!!!!
• But we just want to reuse our own
projects
• And we never will release it as a library for
people to use

4. • we need something could be done in your life
class User < ActiveRecord::Base
devise :database_authenticatable, :registerable,
:rememberable, :trackable, :token_authenticatable, :validatable,
:recoverable, :rememberable, :trackable, :validatable
end
• that code costs you >1 week, but you only got paid 100
RMB???????
• and you have a whole projects to be rewritten in that
way???????????????????????????????????

5. What we get for
Namespace less?
• reuse your projects (not just a small part of code)
• for example, you are a site building company
• you have copy/paste your cms, news system, fancy image uploader, wysiwyg editor,
navigation config...
• but every client just wants a fancy different looking...
• easy to inherits & override anything
• controllers
Hey, I am still copy & paste.
• models
How is the Engine?
• views?
• helper
• write code without namespace
• MyAwsomeEngine::MyAwsomeModel
• MyAwsomeModel I am still learning the Devise
code structure.
• something robust, not monkey hacking
It just updates again...

6. How?

7. • Add Namespace less placeholders for
models & controllers
• Do inline Namespace::ClassName
definition
• Write code without Namespace
• That’s probably all...

8. in your engine:
/app/models/department.rb
in your project:
/app/models/department.rb
Which one will be used?

9. in your engine:
/app/models/hr/department.rb
in your project:
/app/models/department.rb
class department < Hr::Department
end
To fix it!

10. in your engine:
/app/models/hr/department.rb
/app/models/department.rb
in your project:
/app/models/department.rb
class department < Hr::Department
end
To fix it, also make
engine not complain!

11. module Hr
class DepartmentsController < ApplicationController
def index
@departments = Department.all # Hr::Department
end
end
end
class Hr::DepartmentsController < ApplicationController
def index
@departments = Department.all # Department
end
end

12. A model override
sample
class Hr::Employee < ActiveRecord::Base
def full_name
[first_name, last_name].join(" ")
# Shaokun Wu
end
end
class Employee < Hr::Employee
def full_name
[last_name, first_name].join
# 伍少坤
end

13. Controllers
• The same as models...

14. What a about View?
• You cannot inherits your view
• But you could override them

15. Helper
• Not so sure, perhaps something like...
Module Hr::ApplicationHelper
def hello_world; end
end
Module ApplicationHelper
include Hr::ApplicationHelper
def hello_world
end
end

16. Find a better place for
the placeholder files
class MyEngine < Rails::Engine
paths["app/controllers"] << "lib/placeholders/controllers"
end

17. How to use the engine
• in your Gemfile
gem 'hr', :path => "../hr"
• then
$ bundle install
• copy the migration files
$ rake hr_engine:install:migrations

18. Some Tips
• add your engine as a submodule instead of a pure Gem
• your engine is not perfect
• bundle still cannot handle same name of gem in different
group??
• write engine rake task to generate models & controllers in your
projects
• try with mongoid, but be careful of the namespace
• class Department < Hr::Department
• # still get hr_departments as the collection name...
• # of course, you could set the collection name in mongoid :)

19. Read this carefully
• http://api.rubyonrails.org/classes/Rails/
Engine.html

20. The code here
• https://github.com/shaokun/nl-engine