The document discusses Merb slices, which are full-stack mini-Merb applications that can be shared between applications. Some key points: 1) Slices include full MVC components, assets, routes, and namespacing, and can be distributed as gems. 2) Developers can install slices with gems, configure them in their application, and access them at default URL paths. 3) Slices have rake tasks for common functions like copying assets, patching code, and running specs. They can also be customized through patching, configuration, and custom actions/views/routes. 4) The document provides instructions for creating a sample blog slice, including generating the structure, initializing settings,

1. Merb Slices

2. Slice By Who?
• Fabien Franzen a.k.a. loob2
• Actually remembers Merb 0.0.0.1 a.k.a ‘the pastie’
• Representing Belgium (or maybe not...)

3. Who Am I?
• Daniel Neighman a.k.a. hassox
• Engine Yarder
• Proud Aussie

4. What’s a Merb Slice?

5. What’s a Merb Slice?
• Full Stack Mini Merb
Application
• Designed to be shared
between applications
• Built on Merbs Public
API

6. What’s Included?
• Full MVC Components
• Assets
• Routes
• Full Namespacing
• Hot Code Loading /
Unloading
• Distribution as Gems

7. Slice It

8. Slice It
• Get it:
➡ $ sudo gem install blog_slice

9. Slice It
• Get it:
➡ $ sudo gem install blog_slice
• Install it:
➡ $ rake slices:blog_slice:install

10. Configure It

11. Configure It
config/init.rb
dependency quot;merb-slicesquot;
dependency quot;blog_slicequot;

12. Configure It
config/init.rb
dependency quot;merb-slicesquot;
dependency quot;blog_slicequot;
config/routes.rb
Merb::Router.prepare do
all_slices
end

13. Run It

14. Run It
$ merb

15. Use It

16. Use It
• By Default, your slice is available at:
• http://localhost:4000/blog_slice

17. Use It
• By Default, your slice is available at:
• http://localhost:4000/blog_slice
• Get the posts:
• http://localhost:4000/blog_slice/posts

18. Rake It

19. Rake It
There are many rake tasks available

20. Rake It
There are many rake tasks available

21. Rake It
There are many rake tasks available
• rake slices

22. Rake It
There are many rake tasks available
• rake slices
• rake slices:install_as_gem

23. Rake It
There are many rake tasks available
• rake slices
• rake slices:install_as_gem
• rake -T slices:blog_slice

24. Common Rake Tasks
• rake slices:blog_slice:copy_assets
• rake slices:blog_slice:patch
• rake slices:blog_slice:freeze(:*)
• rake slices:blog_slice:migrate
• rake slices:blog_slice:spec

25. Customize It
• It’s just ruby. Monkey Patch it
• Use the “patch” rake task
• Slice code is in your app:
• Merb.root/slices/blog_slice

26. Custom Options

27. Custom Options
• Each Slice has a Configuration Hash
• Merb::Slices::config[:blog_slice]

28. Custom Options
• Each Slice has a Configuration Hash
• Merb::Slices::config[:blog_slice]
• Aliased To:
• BlogSlice[]

29. Custom Actions

30. Custom Actions
Adding the Action to the controller
$ rake slices:blog_slice:patch

31. Custom Actions
Adding the Action to the controller
$ rake slices:blog_slice:patch
Edit: Merb.root/blog_slices/app/controllers/posts.rb
def publish
@post = Post.first(:permalink => params[:permalink])
if @post.publish!
redirect slice_url(:post, @post), :message => quot;Posts Publishedquot;
else
render :edit
end
end

32. Custom Views

33. Custom Views
$ rake slices:blog_slice:freeze:views

34. Custom Views
$ rake slices:blog_slice:freeze:views
Available in:
Merb.root/slices/blog_slice/app/views

35. Custom Views
$ rake slices:blog_slice:freeze:views
Available in:
Merb.root/slices/blog_slice/app/views
Add templates for additional formats

36. Custom Layout

37. Custom Layout
• By Default the Slice layout is used

38. Custom Layout
• By Default the Slice layout is used
Merb::BootLoader.after_app_loads do
BlogSlice[:layout] = :blog_slice_layout
end

39. Custom Models

40. Custom Models
Stubs or Freeze?
$ rake slices:blog_slice:freeze:models

41. Custom Models
module BlogSlice
class Post
property :published, Boolean
property :published_at, DateTime
Stubs or Freeze?
def publish!
self.published = true
$ rake slices:blog_slice:freeze:models self.published_at = DateTime.now
save
end
end # Post
end # BlogSlice

42. Custom Routes
Merb::Router.prepare do
add_slice(:blog_slice, :path_prefix => quot;blogquot;, :default_routes => nil) do
identify BlogSlice::Post => :permalink do
match(quot;/posts/:permalink/publishquot;).
to(:controller => quot;postsquot;, :action => quot;publishquot;).
name(:publish)
end
end
end

43. Prefix URL Paths

44. Prefix URL Paths
• Setup a Path Prefix
• add_slice(:blog_slice, quot;awesomequot;)
• Example: /awesome/posts

45. Prefix Named Routes

46. Prefix Named Routes
• Default name_prefix on named routes:
• add_slice(:blog_slice)
• url(:blog_slice_posts)

47. Prefix Named Routes
• Default name_prefix on named routes:
• add_slice(:blog_slice)
• url(:blog_slice_posts)
• Setup a Name Prefix
• add_slice(:blog_slice, :name_prefix => quot;blogquot;)
• url(:blog_posts)

48. Write It

49. Development Flow

50. Development Flow
•Generate
•Write
•Use
•Write
•Use
•Finish - Install

51. Development Flow
•Generate
•Write
•Use
•Write
•Use
$ slice
•Finish - Install

52. Generate It
$ merb-gen slice blog_slice

53. New Slice Structure
blog_slice blog_slice
|-app |-public
|---controllers |---images
|---helpers |---javascripts
|---models |---stylesheets
|---views |-spec
|-----layout |---controllers
|-----main |-stubs
|-lib |---app
|---blog_slice |-----controllers
|-pkg |-----models

54. Some Important Files
blog_slice/lib
blog_slice
merbtasks.rb
slicetasks.rb < Here be dragons
spectasks.rb
blog_slice.rb

55. Initialize It

56. Initialize It
• blog_slice.rb is where the slice initializes

57. Initialize It
• blog_slice.rb is where the slice initializes
• Dependencies

58. Initialize It
• blog_slice.rb is where the slice initializes
• Dependencies
• Router

59. Initialize It
• blog_slice.rb is where the slice initializes
• Dependencies
• Router
• Hooks

60. Fake It
• Setup a fake “host app” env in config/init.rb
• config/init.rb is not used normally

61. Controllers

62. Controllers
• blog_slice/app/controllers/posts.rb
class BlogSlice::Posts < BlogSlice::Application
# Your Controller Code Here
end # Posts

63. Views
• blog_slice/app/views/posts/show.html.haml
• blog_slice/app/views/layouts/application.html.haml

64. Layouts
• blog_slice/lib/blog_slice.rb
Merb::Slices::config[:blog_slice][:layout] ||= :blog_slice

65. slice_url

66. slice_url
• Use slice_url for url generation inside a slice
• slice_url(:controller => ..., :action => ...)
• slice_url(:post, @post)
• slice_url(:merb_auth_slice_password, :login)

67. Models
Namespace your models (you don’t have to)
class BlogSlice::Post
include DataMapper::Resource
property :id, Serial
property :title, String, :lenth => 255
property :body, Text
property :slug, Slug
before :save do
self.slug = self.title unless self.permalink
end
end # BlogSlice::Post

68. Assets

69. Assets
• blog_slice/public
• images, css, javascipt
• Read:
blog_slice/app/helpers/application_helper.rb

70. Images
• blog_slice/public/images
• Helper: image_path(image)

71. Javascript
• blog_slice/public/javascripts
• Helper: javascript_path(javascript)

72. Stylesheets
• blog_slice/public/stylesheets
• Helper: stylesheet_path(style)

73. Install Assets
• rake slices:blog_slice:copy_assets

74. Route It
blog_slice/lib/blog_slice.rb (the init.rb)
def self.setup_router(scope)
scope.identify Post => :slug do
resource :posts
end
end

75. Hook It

76. Hook It
• loaded

77. Hook It
• loaded
• init

78. Hook It
• loaded
• init
• activate

79. Hook It
• loaded
• init
• activate
• deactivate

80. Hooks - loaded
• Slice Code Loads
• Hook - loaded
• Boot Loader LoadClasses

81. Hooks - init, activate
• Slice Hook - init
• BootLoader AfterAppLoads
• Slice Hook - activate: triggered by
Merb::Slices.activate(BlogSlice)

82. Hooks - deactivate
• Triggered by
Merb::Slices.deactivate(BlogSlice)

83. Spec It
• Specs go in blog_slice/spec
• rake -T spec
• Spec your slice like an app

84. Spec It - Setup
• Setup the routes:
before :all do
Merb::Router.prepare do
add_slice(:blog_slice)
end if standalone?
end

85. Distribute It
• rake gemspec
• rake install

86. Questions?