joshsaintjacque

class User < TotallyNotActiveRecord
  # ...Other functions on the User model...
  
  def create(data=nil)
    # Create the user record in the database
    super(data)
    
    # Send a welcome email
    WelcomeEmail.send(email) if email.present?
    

joshsaintjacque

class Driver
  attr_reader :vehicle
  
  def initialize(vehicle)
    @vehicle = vehicle
  end
  
  def floor_it
    vehicle.accelerate_to(120)
  end

joshsaintjacque

class Driver
  attr_reader :car
  
  def initialize
    @car ||= Car.new
  end
  
  def floor_it
    car.accelerate_to(120)
  end

joshsaintjacque

class TextReport < ReportTemplate
  def format_report
    # arrange financial data into plain text report
  end
end

class HTMLReport < ReportTemplate
  def format_report
    # arrange financial data into HTML report
  end

joshsaintjacque

class ReportTemplate
  def generate_report!
    retrieve_financial_data
    format_report
    send_to_stakeholders
  end

  private

  def retrieve_financial_data

joshsaintjacque

class Report
  def generate_report!
    retrieve_financial_data
    format_report
    send_to_stakeholders
  end

  private

  def retrieve_financial_data

joshsaintjacque

defaults write com.apple.dock persistent-apps -array-add '{"tile-type"="spacer-tile";}' && killall Dock

joshsaintjacque

While attempting to explain JavaScript's reduce method on arrays, conceptually, I came up with the following - hopefully it's helpful; happy to tweak it if anyone has suggestions.

Intro

JavaScript Arrays have lots of built in methods on their prototype. Some of them mutate - ie, they change the underlying array in-place. Luckily, most of them do not - they instead return an entirely distinct array. Since arrays are conceptually a contiguous list of items, it helps code clarity and maintainability a lot to be able to operate on them in a "functional" way. (I'll also insist on referring to an array as a "list" - although in some languages, List is a native data type, in JS and this post, I'm referring to the concept. Everywhere I use the word "list" you can assume I'm talking about a JS Array) This means, to perform a single operation on the list as a whole ("atomically"), and to return a new list - thus making it much simpler to think about both the old list and the new one, what they contain, and

joshsaintjacque

# Solution to https://www.reddit.com/r/csinterviewproblems/comments/3xfzwt/given_an_array_of_integers_and_a_partition_index/
# Given an array of integers and a partition index, switch the two partitions of the array in O(1) space and O(n) time.
def partition(enum, enum_index)
  enum.partition.with_index {|value, index| index >= enum_index}.flatten
end

joshsaintjacque

Libraries

• jQuery - The de-facto library for the modern age. It makes things like HTML document traversal and manipulation, event handling, animation, and Ajax much simpler with an easy-to-use API that works across a multitude of browsers.
• Backbone - Backbone.js gives structure to web applications by providing models with key-value binding and custom events, collections with a rich API of enumerable functions, views with declarative event handling, and connects it all to your existing API over a RESTful JSON interface.
• AngularJS - Conventions based MVC framework for HTML5 apps.
• Underscore - Underscore is a utility-belt library for JavaScript that provides a lot of the functional programming support that you would expect in Prototype.js (or Ruby), but without extending any of the built-in JavaScript objects.
• lawnchair - Key/value store adapter for indexdb, localStorage