blairanderson

Dependency Injection in Ruby 07 Oct 04

Introduction

At the 2004 Ruby Conference, Jamis Buck had the unenviable task to explain Dependency Injection to a bunch of Ruby developers. First of all, Dependency Injection (DI) and Inversion of Control (IoC) is hard to explain, the benefits are subtle and the dynamic nature of Ruby make those benefits even more marginal. Furthermore examples using DI/IoC are either too simple (and don’t convey the usefulness) or too complex (and difficult to explain in the space of an article or presentation). I once attempted to explain DI/IoC to a room of Java programmers (see onestepback.org/articles/dependencyinjection/), so I can’t pass up trying to explain it to Ruby developers.

Thanks goes to Jamis Buck (the author of the Copland DI/IoC framework) who took the time to review this article and provide feedback.

What is Dependency Injection?

jbrowning

# The $provide service is used to override an injected dependency

# Bad - results in Error: [ng:areq] Argument 'fn' is not a function, got Object
module 'someModule', ($provide) ->
  $provide.value "SomeService", SomeMock

# Good
module 'someModule', ($provide) ->
  $provide.value "SomeService", SomeMock
  null

ryanb

class TasksController < ApplicationController
  def update
    tracker = TaskTracker.new(@task)
    if @task.update_attributes(params[:task])
      TaskPusher.new(tracker, socket_id).push_changes
      TaskMailSender.new(tracker, current_user).deliver_email
      # success response
    else
      # failure respond
    end

blazarecki

<?php

namespace Widop\Mink\Extension;

/**
 * Dictionary to manage popups.
 * 
 * @author Benjamin Lazarecki <[email protected]>
 */
trait PopupDictionary

panthomakos

#!/usr/bin/env ruby

require 'benchmark'

REGEXPS = [
  /^no such file to load -- (.+)$/i,
  /^Missing \w+ (?:file\s*)?([^\s]+.rb)$/i,
  /^Missing API definition file in (.+)$/i,
  /^cannot load such file -- (.+)$/i,
]

evo42

( function ( window, undefined ) {
	var Aloha = window.Aloha || ( window.Aloha = {} );
	
	Aloha.settings = {
		logLevels: { 'error': true, 'warn': true, 'info': true, 'debug': false, 'deprecated': true },
		errorhandling: false,
		ribbon: false,
		locale: 'en',
		floatingmenu: {
			width: 630,

memphys

<?php

    protected function _initDoctrine()
    {
    	$options = $this->getOptions();
    	$doctrinePath = $options['includePaths']['library']; 
    	require_once $doctrinePath . '/Doctrine/Common/ClassLoader.php';
	$autoloader = Zend_Loader_Autoloader::getInstance();

    	$doctrineAutoloader = array(new \Doctrine\Common\ClassLoader(), 'loadClass');