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To Null Or Not To Null

• Null in Strongly Typed Languages
• Downsides of Null
• Limiting Null Usage
• Best Practices

Null in Strongly Typed Languages

The Go standard library does not have nullable values for basic types like strings and integers, which can be confusing for someone coming from weak or dynamically typed languages like Ruby, Python, or JavaScript. Here's a comparison of how Ruby sets variable defaults compared to Go:

choxi

#------------------------------------------------------------------

#
#   Bayes Optimal Classifier
#
#   In this quiz we will compute the optimal label for a second missing word in a row
#   based on the possible words that could be in the first blank
#
#   Finish the procedurce, LaterWords(), below
#

choxi

$modal = $("<div><ul></ul></div>")
$modal.css({
  position: "absolute",
  height: "500px",
  width: "500px",
  background: "white",
  border: "1px solid gray",
  padding: "10%",
  margin: "5% 25%"
});

choxi

Installation Update

A few of you have been having a lot of trouble with the "Laptop" script that's supposed to install a bunch of tools for you and I apologize for that, there are actually only 2 main tools that you need to have installed. If you haven't already done the developer setup yet, please follow these updated instructions instead:

Note: We'll be checking version numbers to make sure things were installed correctly, it's completely OK if your version number is not exactly the same as the ones I've given as examples below.

OSX Lion

If you're not on OS X Lion, you will need to upgrade to it. I should have mentioned that as an up front prerequisite, so if you do need to upgrade please let me know and I'll refund you $30 to cover the cost of the upgrade.

choxi

namespace :db do
  namespace :migrate do
    desc "create an empty timestamped migration file"
    task :new do
      raise "Usage: rake db:migrate:new NAME='create_cohorts'" if ENV["NAME"].nil?

      current_migration = Dir.glob("./db/migrate/[0-9]*_*.rb").collect do |file|
        File.basename(file).split("_").first.to_i
      end.max.to_i

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require 'spec_helper'

describe "Bookmarks" do
  describe "GET /bookmarks" do
    context "when user is not logged in" do
      it "should redirect a to home" do
        get bookmarks_path
        response.should redirect_to(root_url)
      end
    end

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# This file will be copied to ~/.emscripten if that file doesn't exist. Or, this is that copy.
# IMPORTANT: Edit the *copy* with the right paths!

EMSCRIPTEN_ROOT = os.path.expanduser('~/Dev/emscripten') # this helps projects using emscripten find it

LLVM_ROOT = os.path.expanduser('/usr/local/Cellar/llvm/3.0/bin')

# See below for notes on which JS engine(s) you need
NODE_JS = 'node'
SPIDERMONKEY_ENGINE = [os.path.expanduser('~/Dev/mozilla-central/js/src/js'), '-m', '-n']

choxi

!!! 5
%html
  %head
    %title welcome visitor
  %body
    %h1 hello there

choxi

require 'rubygems'
require 'sinatra'

configure do
  require 'redis'
  require 'uri'
  REDISTOGO_URL = ENV["REDISTOGO_URL"]
  uri = URI.parse(REDISTOGO_URL)
  REDIS = Redis.new(:host => uri.host, :port => uri.port, :password => uri.password)
end

choxi

(master)⚡ % rake assets:precompile --trace                                                                                       ~/code/Bieber
** Invoke assets:precompile (first_time)
** Execute assets:precompile
/Users/roshan/.rvm/rubies/ruby-1.9.2-p290/bin/ruby /Users/roshan/.rvm/gems/ruby-1.9.2-p290@holla/bin/rake assets:precompile:all RAILS_ENV=production RAILS_GROUPS=assets --trace
** Invoke assets:precompile:all (first_time)
** Execute assets:precompile:all
** Invoke assets:precompile:primary (first_time)
** Invoke assets:environment (first_time)
** Execute assets:environment
** Invoke tmp:cache:clear (first_time)