Stephen Puiszis stephen-puiszis

Polymorphic Associations reversed

It's pretty easy to do polymorphic associations in Rails: A Picture can belong to either a BlogPost or an Article. But what if you need the relationship the other way around? A Picture, a Text and a Video can belong to an Article, and that article can find all media by calling @article.media

This example shows how to create an ArticleElement join model that handles the polymorphic relationship. To add fields that are common to all polymorphic models, add fields to the join model.

Stevey's Google Platforms Rant

I was at Amazon for about six and a half years, and now I've been at Google for that long. One thing that struck me immediately about the two companies -- an impression that has been reinforced almost daily -- is that Amazon does everything wrong, and Google does everything right. Sure, it's a sweeping generalization, but a surprisingly accurate one. It's pretty crazy. There are probably a hundred or even two hundred different ways you can compare the two companies, and Google is superior in all but three of them, if I recall correctly. I actually did a spreadsheet at one point but Legal wouldn't let me show it to anyone, even though recruiting loved it.

I mean, just to give you a very brief taste: Amazon's recruiting process is fundamentally flawed by having teams hire for themselves, so their hiring bar is incredibly inconsistent across teams, despite various efforts they've made to level it out. And their operations are a mess; they don't real

	user nginx;
	worker_processes 5;

	error_log /var/log/nginx.error.log;
	pid /var/run/nginx.pid;

	events {
	worker_connections 1024;
	}

	connection = Faraday::Connection.new('http://example.com') do \|builder\|
	builder.request :url_encoded # for POST/PUT params
	builder.adapter :net_http
	end

	# same as above, short form:
	connection = Faraday.new 'http://example.com'

	# GET
	connection.get '/posts'

	# db/migrate/20110714024435_split_author.rb
	class SplitAuthor < ActiveRecord::Migration
	def self.up
	Post.where(:author=>nil).each do \|p\|
	author = Author.create!(:name => p.author_name,
	:account_id => p.account_id)
	p.author = author
	p.save!
	end
	end

	class InvitationsController < Devise::InvitationsController

	# GET /resource/invitation/accept?invitation_token=abcdef
	def edit
	if params[:invitation_token] && self.resource = resource_class.to_adapter.find_first( :invitation_token => params[:invitation_token] )
	session[:invitation_token] = params[:invitation_token]
	render :edit
	else
	set_flash_message(:alert, :invitation_token_invalid)
	redirect_to after_sign_out_path_for(resource_name)

	#Model

	@user.should have(1).error_on(:username) # Checks whether there is an error in username
	@user.errors[:username].should include("can't be blank") # check for the error message

	#Rendering
	response.should render_template(:index)

	#Redirecting
	response.should redirect_to(movies_path)

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD

	newpg=9.6.1 # set to new PG version number
	oldpg=`pg_config --version \| cut -d' ' -f2`

	# PG 96. upgrades the readline to v7, which breaks anything linked against readline v6, like ruby via ruby-build.
	# I think this should prevent it from installing v7. But if weird shit happens with various rubies,
	# you'll have to reinstall them.
	brew pin readline

	# Stop current Postgres server
	brew services stop postgresql

	require 'rubygems'
	require 'middleman/rack'

	protected_middleman = Rack::Auth::Basic.new(Middleman.server) do \|username, password\|
	[username, password] == ['theuser', 'thepassword']
	end

	run protected_middleman