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0xFA1A8B6d57B252b8307770A569023f6568DF54E3

kwaters12

Ch.2 - The Grammar
- Blocked comments /* */
- Line comments //
- /* */ can mess up regular expressions, so it is recommended to stick to //

Names
- names are strings. A list of reserved words:
abstract
boolean break byte
case catch char class const continue

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Algorithm - any well-defined computational procedure that takes some value, or set of values, as input and produces some value, or set of values as output.

Runtime Analysis
- One of the most important aspects of an algorithm is how fast it is.
- Worst-case runtime - how long it would take the algorithm to run if it were given the most insidious of all possible inputs.
- Average-case runtime - how long it would take the algorithm to run if it were given all possible inputs.
- worst-case is often easier to reason about, and therefore is more frequently used as a benchmark.

Approximate completion time for algorithms, N = 100

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-- Workflow - from http://blog.littleblimp.com/post/53942611764/direct-uploads-to-s3-with-rails-paperclip-and

Our app will work as follows:

User uploads their file directly to a temporary directory on S3
A form callback posts the temporary file URL to our app
Our app creates a new Document object, sets some initial data from the temporary S3 file, then queues a background process to move the temporary file to the location that Paperclip expects it to be and to process thumbnails if required
Show users a message if they visit a file page while its still being processed

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module Computers
  class Apple
  end
end

module Fruits
  class Apple
  end
end

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1. Retrieving Objects from the Database
Finder methods. All return an instance of ActiveRecord::Relation:
  bind
  create_with
  eager_load
  extending
  from
  group
  having
  includes

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:_delete
:title
session
request
cookies
response
post
send_data
send_file

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1. rails g migration add_like_to_projects like_counter:integer
2. routes.rb ->
  resources :projects do
    get :like, on: :member
  end 
3. projects_controller.rb ->
  def like
    session[:project_ids] ||= []
    
    if session[:project_ids].include? params[:id].to_i

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gem 'bootstrap-sass'
gem 'quiet_assets'
gem 'better_errors'
gem 'formtastic'
gem 'formtastic-bootstrap'

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Session
- stores small amounts of data that will be persisted between requests.
- only available in the controller and the view
- Session storage mechanisms:
  ActionDispatch::Session::CookieStore - Stores everything on the client.
  ActionDispatch::Session::CacheStore - Stores the data in the Rails cache.
  ActionDispatch::Session::ActiveRecordStore - Stores the data in a database using Active Record. (require activerecord-session_store gem).
  ActionDispatch::Session::MemCacheStore - Stores the data in a memcached cluster (this is a legacy implementation; consider using CacheStore instead).
- stores unique ID for each session as a cookie
- CookieStore holds around 4kb of data.