andrey pechorin pechorin

My issues with Modules

In researching topics for RailsCasts I often read code in Rails and other gems. This is a great exercise to do. Not only will you pick up some coding tips, but it can help you better understand what makes code readable.

A common practice to organize code in gems is to divide it into modules. When this is done extensively I find it becomes very difficult to read. Before I explain further, a quick detour on instance_eval.

You can find instance_eval used in many DSLs: from routes to state machines. Here's an example from Thinking Sphinx.

class Article &lt; ActiveRecord::Base

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

tmux cheatsheet

As configured in my dotfiles.

start new:

tmux

start new with session name:

YARD CHEATSHEET http://yardoc.org

May 2020 - updated fork: https://gist.github.com/phansch/db18a595d2f5f1ef16646af72fe1fb0e

cribbed from http://pastebin.com/xgzeAmBn

Templates to remind you of the options and formatting for the different types of objects you might want to document using YARD.

Modules

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

	-- http://stackoverflow.com/questions/1124603/grouped-limit-in-postgresql-show-the-first-n-rows-for-each-group
	-- http://www.postgresql.jp/document/9.2/html/tutorial-window.html

	CREATE TABLE empsalary (
	depname varchar(10) not null
	, empno integer not null
	, salary integer not null
	);

	INSERT INTO empsalary (depname, empno, salary) VALUES ('develop', 11, 5200);

	-- show running queries (pre 9.2)
	SELECT procpid, age(clock_timestamp(), query_start), usename, current_query
	FROM pg_stat_activity
	WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%'
	ORDER BY query_start desc;

	-- show running queries (9.2)
	SELECT pid, age(clock_timestamp(), query_start), usename, query
	FROM pg_stat_activity
	WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%'

	# example
	# date = Date.today
	# ExchangeWithFallback.new(
	# SynchronizedRates.new(
	# DoubleConvertThrough.new('RUB',
	# InverseRatesFor.new( {from: 'RUB'},
	# RatesUpdatedWithFallback.new(
	# ActiveRecordRates.new(CurrencyRate.where(date: date, bank: 'cbr')),
	# LazyRates.new { CentralBankOfRussia.new.update_rates(date) } )))))

	brew update
	brew versions FORMULA
	cd `brew --prefix`
	git checkout HASH Library/Formula/FORMULA.rb # use output of "brew versions"
	brew install FORMULA
	brew switch FORMULA VERSION
	git checkout -- Library/Formula/FORMULA.rb # reset formula

	## Example: Using Subversion 1.6.17
	#

	# ...

	gem 'carrierwave'
	gem 'fog', '~> 1.0.0' # Need to specify version, as carrierwave references older (0.9.0) which doesn't allow configuration of Rackspace UK Auth URL