Ruby on Rails 4.2 個人的な気になるポイント ref: http://qiita.com/shu_0115/items/c04ebcf9b4d4fa8b76ea

file0.txt

get '/posts', to: MyRackApp    => (変更不要)
get '/posts', to: 'post#index' => (変更不要)
get '/posts', to: 'posts'      => get '/posts', controller: :posts
get '/posts', to: :index       => get '/posts', action: :index

file1.txt

# 良くない例
root_path('controller' => 'posts', 'action' => 'index')

# 良い例
root_path(controller: 'posts', action: 'index')

file2.txt

after_filter          => after_action
append_after_filter   => append_after_action
append_around_filter  => append_around_action
append_before_filter  => append_before_action
around_filter         => around_action
before_filter         => before_action
prepend_after_filter  => prepend_after_action
prepend_around_filter => prepend_around_action
prepend_before_filter => prepend_before_action
skip_after_filter     => skip_after_action
skip_around_filter    => skip_around_action
skip_before_filter    => skip_before_action
skip_filter           => skip_action_callback

file3.txt

pp topic

#<Topic:0x007fb93696bcb0
 id: 1,
 title: "The First Topic",
 author_name: "David",
 author_email_address: "david@loudthinking.com",
 written_on: 2003-07-16 14:28:11 UTC,
 bonus_time: 2000-01-01 14:28:00 UTC,
 last_read: Thu, 15 Apr 2004,
 content: "Have a nice day",
 important: nil,
 approved: false,
 replies_count: 1,
 unique_replies_count: 0,
 parent_id: nil,
 parent_title: nil,
 type: nil,
 group: nil,
 created_at: 2014-05-18 21:31:53 UTC,
 updated_at: 2014-05-18 21:31:53 UTC>