alassek

Why We Should Inject Dependencies

Dependency Injection frameworks have existed for a long time, but Rubyists have traditionally avoided doing this, likely because it is perceived as being unnecessary complexity.

However, the "simplicity" afforded by not doing this has negative effects, as this document attempts to demonstrate. Ruby's flexibility allows us to approach DI in a much more friendly way than e.g. Java.

1. The Distinction Between Dependencies and Arguments

Frequently, parameters to an object are passed as a combination of initialization params and method arguments with no clear difference.

alassek

require "global_id"

module Sidekiq
  module GlobalIDMiddleware
    class Processor
      def call(_worker_class, job, *)
        job["args"].map!(&method(:process))
        yield
      end

alassek

def Redis.Mutex(name, expires:, redis: Redis.current, &block)
	raise ArgumentError, "block required" unless block_given?

	if block.arity.zero?
		success = block
		block = proc do |on|
			on.success(&success)
			on.failure(&proc{})
		end
	end

alassek

type Maybedoer struct {
	err error	
}

func (m Maybedoer) Maybe(f func() error) {
	if m.err == nil {
		c.err = f()	
	}
}

alassek

namespace :db do
  desc "Do a clean reset of your DB from a backup file"
  task refresh: [:environment, :check_protected_environments] do
    filename = ARGV.last
    jobs     = ENV.fetch('JOBS', 2)
    database = ActiveRecord::Base.connection.current_database

    abort "Usage: rails db:refresh filename" if filename == 'db:refresh'
    abort "Can't find: #{filename}" unless File.exists? filename
    abort "Can't find pg_restore, make sure it is in your $PATH" unless system "which", "pg_restore"

alassek

Keybase proof

I hereby claim:

• I am alassek on github.
• I am alassek (https://keybase.io/alassek) on keybase.
• I have a public key ASCER3RZ4eL9jqSNbXVviFayarCOAT2JXki5SwZ6hhHopwo

To claim this, I am signing this object:

alassek

I've been doing some work lately with JSON documents in PostgreSQL using jsonb columns. You can query these documents using a GIN index in PG, but the syntax can be a little cumbersome

SELECT "events".* FROM "events" WHERE "events"."body" @> '{"shift":{"user_id":2}}'

You have to construct the right side of the query as a JSON string, which is a bit annoying. So I wondered if I could adapt Arel to do the tedious stuff for me.

alassek

class ApplicationController < ActionController::Base
  before_filter :require_authentication
  
private

  def require_authentication
    unless current_certificate.verify(public_key)
      head :forbidden
    end
  end

alassek

/**
 *  `window.location` is a BAD api. Doesn't have a prototype, 'too much recursion' error
 *  if you try to inspect the constructor. Monkey-patching causes random disappearances
 *  of the monkey-patched function in Chrome, cloning causes 'too much recursion' in FF.
 *
 *  This is what I'm reduced to. ಠ_ಠ
 **/
(function () {

  function Location () {

alassek

# By Henrik Nyh <http://henrik.nyh.se> 2008-01-30.
# Free to modify and redistribute with credit.

require "rubygems"
require "hpricot"

module TextHelper

  # Like the Rails _truncate_ helper but doesn't break HTML tags or entities.
  def truncate_html(text, max_length = 30, ellipsis = "...")