Konstantinos Stratis kstratis

Dynamic Dispatch
Dynamic Method
Ghost Methods
Dynamic Proxies
Blank Slate
Kernel Method
Flattening the Scope (aka Nested Lexical Scopes)
Context Probe
Class Eval (not really a 'spell' more just a demonstration of its usage)
Class Macros

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

A Primer on Ruby Method Lookup

Method lookup is a simple affair in most languages without multiple inheritance. You start from the receiver and move up the ancestors chain until you locate the method. Because Ruby allows you to mix in modules and extend singleton classes at runtime, this is an entirely different affair.

I will not build contrived code to exemplify the more complicated aspects of Ruby method lookup, as this will only serve to confuse the matter.

When you pass a message to an object, here is how Ruby finds what method to call:

1. Look within singleton class

use Rack::Lint # gives more descriptive error messages when responses aren't valid

class LogIt
  def initialize(app)
    @app = app
  end
  def call(env)
    status, headers, body  = @app.call(env)
    body.map { |chunk| p "LogIt: #{chunk}" }

	# lib/tasks/db.rake
	namespace :db do

	desc "Dumps the database to db/APP_NAME.dump"
	task :dump => :environment do
	cmd = nil
	with_config do \|app, host, db, user\|
	cmd = "pg_dump --host #{host} --username #{user} --verbose --clean --no-owner --no-acl --format=c #{db} > #{Rails.root}/db/#{app}.dump"
	end
	puts cmd

	# Automatically instal the latest nginx
	wget -O - http://nginx.org/keys/nginx_signing.key \| sudo apt-key add -

	#Make a backup copy of your current sources.list file
	sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak

	#Now copy the following repositories to the end of ` /etc/apt/sources.list`
	echo "deb http://nginx.org/packages/mainline/ubuntu/ trusty nginx" \| sudo tee -a /etc/apt/sources.list
	echo "deb-src http://nginx.org/packages/mainline/ubuntu/ trusty nginx" \| sudo tee -a /etc/apt/sources.list

	# config/initializers/compression.rb

	Rails.application.configure do
	# Use environment names or environment variables:
	# break unless Rails.env.production?
	break unless ENV['ENABLE_COMPRESSION'] == '1'

	# Strip all comments from JavaScript files, even copyright notices.
	# By doing so, you are legally required to acknowledge
	# the use of the software somewhere in your Web site or app:

	var Dialog = React.createClass({
	render: function() {
	// 1) render nothing, this way the DOM diff will never try to do
	// anything to it again, and we get a node to mess with
	return React.DOM.div();
	},

	componentDidMount: function() {
	// 2) do DOM lib stuff
	this.node = this.getDOMNode();

	var React = require('react/addons');
	var Table = require('./table.jsx');
	var rows = [
	{
	'id' : 1,
	'foo': 'bar'
	},
	{
	'id' : 2,
	'foo': 'baarrrr'

	let csrfToken = 'lololololol';
	let axiosDefaults = require('axios/lib/defaults');
	axiosDefaults.headers.common['X-CSRF-Token'] = csrfToken;