rlburkes

# Wouldn't it be great if you could have STI like functionality
# without needing to encode strings of class names in the database?
# Well today is your lucky day! Discriminable Model is here to help.
#
# Simply specify your models desired type column, and provide a block to
# do the discrimination. If you want the whole STI-esque shebang of properly
# typed finder methods you can supply an array of 'discriminate_types' that will
# be used to apply an appropriate type.
#
# class MyModel < ActiveRecord::Base

SamSaffron

# speed up pluck

class ActiveRecord::Relation

  class RailsDateTimeDecoder < PG::SimpleDecoder
    def decode(string, tuple=nil, field=nil)
      if Rails.version >= "4.2.0"
        @caster ||= ActiveRecord::Type::DateTime.new
        @caster.type_cast_from_database(string)
      else

jcoglan

An ActiveRecord conundrum

I'm going to describe a weird problem I faced when using ActiveRecord today. To protect the innocent, I'm not going to talk about the app I'm actually working on but will instead discuss a hypothetical but isomorphic database design for a clone of the popular blogging platform Tumblr.

Tumblr lets you publish various different sorts of content. We might be tempted to shove all these types in a big STI table, but the types are all quite different from one another and so we give them their own tables.

rietta

#
# PostgreSQL writes two optional commands to the database schema
# file, called db/structure.sql, that can only be run as a root
# database user.  These are not needed actually, so comment them
# out automatically
#
# CREATE EXTENSION IF NOT EXISTS plpgsql WITH SCHEMA pg_catalog;
# COMMENT ON EXTENSION plpgsql IS 'PL/pgSQL procedural language';
#
namespace :db do

ernie

#!/usr/bin/env ruby

class Module
  private

  def delegate(*args)
    dest, prefix = _extract_valid_delegation_options(args.pop)
    _define_delegators(caller_locations.first, prefix, dest, args)
  end

rgs

Falsehoods programmers believe about prices

1. You can store a price in a floating point variable.
2. All currencies are subdivided in 1/100th units (like US dollar/cents, euro/eurocents etc.).
3. All currencies are subdivided in decimal units (like dinar/fils)
4. All currencies currently in circulation are subdivided in decimal units. (to exclude shillings, pennies) (counter-example: MGA)
5. All currencies are subdivided. (counter-examples: KRW, COP, JPY... Or subdivisions can be deprecated.)
6. Prices can't have more precision than the smaller sub-unit of the currency. (e.g. gas prices)
7. For any currency you can have a price of 1. (ZWL)
8. Every country has its own currency. (EUR is the best example, but also Franc CFA, etc.)

bf4

# use inverse_of to 'just work'
class User < ActiveRecord::Base
  has_many :contributions, inverse_of: :user
  has_many :posts, through: :contributions
end

class Post < ActiveRecord::Base
  has_many :contributions, inverse_of: :post
  has_many :contributors, through: :contributions,
    source: :user

carlzulauf

#!/usr/bin/env ruby
 
# thin init script
# install to /etc/init.d/thin

# crazy debian LSB header stuff
### BEGIN INIT INFO
# Provides:          thin
# Required-Start:    $local_fs $remote_fs
# Required-Stop:     $local_fs $remote_fs

dergachev

OS X Screencast to animated GIF

This gist shows how to create a GIF screencast using only free OS X tools: QuickTime, ffmpeg, and gifsicle.

Instructions

To capture the video (filesize: 19MB), using the free "QuickTime Player" application:

avdi

# Generate a module which imports a given subset of module methods
# into the including module or class.
def Methods(source_module, *method_names)
  all_methods = source_module.instance_methods +
    source_module.private_instance_methods
  unwanted_methods = all_methods - method_names
  import_module = source_module.clone
  import_module.module_eval do
    define_singleton_method(:to_s) do
      "ImportedMethods(#{source_module}: #{method_names.join(', ')})"