njvitto

#Deploy and rollback on Heroku in staging and production
task :deploy_staging => ['deploy:set_staging_app', 'deploy:push', 'deploy:restart', 'deploy:tag']
task :deploy_production => ['deploy:set_production_app', 'deploy:push', 'deploy:restart', 'deploy:tag']

namespace :deploy do
  PRODUCTION_APP = 'YOUR_PRODUCTION_APP_NAME_ON_HEROKU'
  STAGING_APP = 'YOUR_STAGING_APP_NAME_ON_HEROKU'

  task :staging_migrations => [:set_staging_app, :push, :off, :migrate, :restart, :on, :tag]
  task :staging_rollback => [:set_staging_app, :off, :push_previous, :restart, :on]

hellerbarde

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

MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

ryanb

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 < ActiveRecord::Base

demisx

belongs_to:

1. Assigning an object to a belongs_to association does not automatically save the object. It does not save the associated object either.

has_one:

1. When you assign an object to a has_one association, that object is automatically saved (in order to update its foreign key).
2. In addition, any object being replaced is also automatically saved, because its foreign key will change too
3. If either of these saves fails due to validation errors, then the assignment statement returns false and the assignment itself is cancelled.
4. If the parent object (the one declaring the has_one association) is unsaved (that is, new_record? returns true) then the child objects are not saved. They will automatically when the parent object is saved.

lfender6445

Pry Cheat Sheet

• Youtube Tutorial 2013

Command Line

• pry -r ./config/app_init_file.rb - load your app into a pry session (look at the file loaded by config.ru)
• pry -r ./config/environment.rb - load your rails into a pry session

Debugger

JunichiIto

This list is based on aliases_spec.rb.

You can see also Module: RSpec::Matchers API.

matcher	aliased to	description
a_truthy_value	be_truthy	a truthy value
a_falsey_value	be_falsey	a falsey value
be_falsy	be_falsey	be falsy
a_falsy_value	be_falsey	a falsy value

nl5887

function transfer
    if test (count $argv) -eq 0
        echo "No arguments specified. Usage:\necho transfer /tmp/test.md\ncat /tmp/test.md | transfer test.md"
        return 1
    end

    ## get temporarily filename, output is written to this file show progress can be showed
    set tmpfile ( mktemp -t transferXXX )

    ## upload stdin or file

isaacs

# Hello, and welcome to makefile basics.
#
# You will learn why `make` is so great, and why, despite its "weird" syntax,
# it is actually a highly expressive, efficient, and powerful way to build
# programs.
#
# Once you're done here, go to
# http://www.gnu.org/software/make/manual/make.html
# to learn SOOOO much more.

brianhempel

require "net/http"

def start_server
  # Remove the X to enable the parameters for tuning.
  # These are the default values as of Ruby 2.2.0.
  @child = spawn(<<-EOC.split.join(" "))
    XRUBY_GC_HEAP_FREE_SLOTS=4096
    XRUBY_GC_HEAP_INIT_SLOTS=10000
    XRUBY_GC_HEAP_GROWTH_FACTOR=1.8
    XRUBY_GC_HEAP_GROWTH_MAX_SLOTS=0