mislav

Jim Weirich:

This is how I explain it… Ruby has Procs and Lambdas. Procs are created with Proc.new { }, lambdas are created with lambda {} and ->() {}.

In Ruby 1.8, proc {} creates lambda, and Ruby 1.9 it creates procs (don't ask).

Lambdas use method semantics when handling parameters, procs use assignment semantics when handling parameters.

This means lambdas, like methods, will raise an ArgumentError when called with fewer arguments than they were defined with. Procs will simply assign nil to variables for arguments that were not passed in.

soulcutter

desc "Launch a Capybara session in a console"
task capyconsole: :environment do
  require "capybara"
  require "pry"

  driver = case ENV.fetch('DRIVER', 'phantomjs')
  when 'phantomjs'
    require "capybara/poltergeist"

    Capybara.register_driver :poltergeist_debug do |app|

iamvery

I watching the demo/use cases video for contracts.ruby and recorded some thoughts.

Use case 1

The use case states that you can avoid bugs like needing string keys instead of symbol keys be enforcing a contract that requires the method input to be a string.

IMO you should instead create a flexible interface that will allow any "stringable" input to be given to the method. That is, use the implicit string conversion methods to_s to make a string of it for indexing into the hash.

Use case 2

iamvery

Conway's Game of Life, written in Ruby

Run the game

ruby driver.rb

Run the specs

rspec game_of_life_spec.rb

iamvery

Conway's Game of Life, written in io

Run the game

io driver.io

Run the specs

io cell_spec.io

iamvery

# Live cells with < 2 living neighbors dies to underpop
# > 3 living neighbors dies to overpop
# Otherwise, lives!
#
# Dead cells with exactly 3 living neighbors is born

# . 0 .
# . 0 .
# . 0 .
#

iamvery

require 'active_record'

class Foo < ActiveRecord::Base
  establish_connection adapter: 'sqlite3', database: ':memory:'

  connection.create_table :foos do |t|
    t.string :name, null: false
  end

  #has_many :bars

iamvery

params = { some: :thing }
oops = {}

def kwargs(some:)
  puts some
end

def hash(args)
  puts args.fetch(:some)
end

iamvery

source 'https://rubygems.org'

gem 'activerecord'
gem 'sqlite3'

iamvery

source 'https://rubygems.org'

gem 'activerecord', '~>3.0'
gem 'sqlite3'