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Snakes and Elephants Playing Nice Together: PHPUnit and py.test with Hudson

Chris Hartjes — Thu, 29 Jul 2010 20:05:27 +0000

These days, it's becoming increasingly harder to find web applications that are homogenous in terms of the tools they use to Get Things Done. The ability to build the web front-end of your site using PHP but a critical part that requires asynchronous processing using Node.js is something that is both exciting and, well, practical. Loosely coupled components, passing messages to each other, is great architecture to try and build if you have both the skills and patience to make it work.

For a project at work, I am using PHP (specifically Zend Framework) for the front-end but are using Python scripts run as a cron-job (and also on-demand when statistical corrections occur) to collect raw stats for a variety of sports, and then generate fantasy point totals for the games we run. I'm already using PHPUnit for tests of the front end, and I decided to to use py.test to test my Python scripts.

Setting up tests in Python was pretty simple. Here's one of my test scripts:

PLAIN TEXT

PYTHON:

import py
import baseball_scoring
def test_batter_empty_data_set():
expected_points = 0
test_data = dict()
test_points = baseball_scoring.batter_points(test_data)
assert expected_points == test_points
def test_batter_simple():
test_data = {
'hits': 4,
'doubles': 1,
'triples': 1,
'home_runs': 1,
'runs_scored': 1,
'rbi': 1,
'stolen_bases': 1,
'league': 'bluejays2010'
}
expected_points = 11
test_points = baseball_scoring.batter_points(test_data)
assert expected_points == test_points
def test_pitcher_empty_data_set():
expected_points = 0
test_data = dict()
test_points = baseball_scoring.pitcher_points(test_data)
assert expected_points == test_points
def test_pitcher_simple():
test_data = {
'wins': 1,
'losses': 0,
'saves': 0,
'strikeouts': 7,
'complete_games': 1,
'shutouts': 1,
'league': 'bluejays2010'
}
expected_points = 25
test_points = baseball_scoring.pitcher_points(test_data)
assert expected_points == test_points

Very similar to tests with PHPUnit, right? So now that I had both PHPUnit tests and py.tests tests (hrm, is there are better way to say that?) to run, I had to figure out how to automatically run them. More specifically, how to get our installation of Hudson to run them.

Getting PHPUnit to play nice with Hudson was relatively easy. I installed the NUnit plugin for Hudson, made sure I installed phpunit, and then I added it's use to my build scripts. However, the strength of Hudson is that with the use of another plugin I could read reports of all those tests. So when things failed, I would not have to look at the console output to figure things out. There's a place in the Hudson config where you can configure this:

Now, I figured that the same thing could be done with py.test. It had an option so that at run-time you could tell it where to put JUnit-compatible test result files. After a little tinkering, I got it to work. First step was adding execution of it to my build script. Here is the latest-and-greatest version of that script:

mkdir /var/www/games-hudson/${BUILD_ID}
cd ${WORKSPACE}/games
/usr/local/zend/bin/php doctrine-cli migrate
cd ${WORKSPACE}/games/tests
/usr/local/zend/bin/phpunit --log-junit=${WORKSPACE}/build/logs/phpunit-results.xml
cd ${WORKSPACE}/games/scripts
/usr/bin/py.test --junitxml=${WORKSPACE}/build/logs/pytest-xmlrunner.xml
cp -R /var/lib/hudson/jobs/${JOB_NAME}/workspace/games/* /var/www/games-hudson/${BUILD_ID}
chmod 777 /var/www/games-hudson/${BUILD_ID}/tmp
rm -rf /var/www/games-hudson/current
ln -sf /var/www/games-hudson/${BUILD_ID} /var/www/games-hudson/current

Next, I then told Huson where it could find the JUnit-compatible files generated by py.test:

So there you have it. Now, when I do a commit and trigger a Hudson build, both my PHPUnit and Python tests get run. And there is output to check, so I don't have to dig through console output to figure things out.

Fun with custom Zend_Views

Chris Hartjes — Thu, 24 Jun 2010 20:03:57 +0000

The other day I had a nice meeting in my basement lair with my co-workers. We laughed. We cried. We had some BBQ'd burgers, and nobody got food poisoning. As we discussed the implementation of our new fantasy gaming platform, I managed to figure out that one requirement was for an admin to upload a header and footer file for a game. "The idea here is to be able to set up a new game for someone without programmer intervention".

After I got over being insulted that a programmer was not required for every tiny tweak to the site (I'm kidding) I tried to figure out how I was going to accomplish this. I'm not a big fan of storing actual HTML content in a database. Call me old-fashioned, but I feel my HTML content belongs on the filesystem, and nowhere else. Besides, it makes it harder to do deployments of code on multiple servers if all the templates aren't there to begin with.

The solution was, of course, obvious: create a custom Zend_View and override stuff until you get it behaving the way you want! The logic for doing this is actually quite simple:

Check to see if the script in question exists in the file system
If not, figure out what template we need to pull from the database.
Read in contents of that script from the database
Write contents to the filesystem

NOTE: I am not sure if this is the most elegant solution for solving this particular problem. I am open to a different solution so long as it meets the same needs.

Since I've made a commitment to doing TDD for this project, naturally I started out with a test:

PLAIN TEXT

PHP:

require_once 'PHPUnit/Framework.php';
require_once 'Zend/Application.php';
// Define path to application directory
if (!defined('APPLICATION_PATH')) {
define('APPLICATION_PATH', realpath(dirname(__FILE__) . '/../../../application'));
}
// Define application environment
if (!defined('APPLICATION_ENV')) {
define('APPLICATION_ENV', (getenv('APPLICATION_ENV') ? getenv('APPLICATION_ENV') : 'test'));
}
// Ensure library/ is on include_path
set_include_path(implode(PATH_SEPARATOR, array(
realpath(APPLICATION_PATH . '/../library'),
get_include_path(),
)));
class Xmlteam_ZFViewTest extends PHPUnit_Framework_TestCase
{
public function setUp()
{
$this->bootstrap = new Zend_Application(
'testing',
APPLICATION_PATH . '/configs/application.ini'
);
parent::setUp();
}
public function tearDown()
{
parent::tearDown();
}
public function testRenderView()
{
$templateData = array(
'league_short_name' => 'testing',
'type' => 'header',
'created_at' => new Doctrine_Expression('NOW()'),
'content' => '
header
'
);
$testTemplate = new Template();
$testTemplate->fromArray($templateData);
$testTemplate->save();
$testView = new Xmlteam_ZFView();
$testView->setScriptPath('./application/views');
$content = $testView->render('testing-header.phtml');
$this->assertTrue(file_exists('./application/views/testing-header.phtml'));
$this->assertEquals($content, $templateData['content']);
$testTemplate->delete();
unlink('./application/views/testing-header.phtml');
}
}

For those wondering, yes all the tests pass.

The "Template" is a Doctrine (1.2) model that represents the table where I'm storing information about the templates. Yes, it has unit tests too. That pass.

So how do we accomplish this? First, I hit up my peeps on Twitter and the advice from Matthew Weier-O'Phinney himself was to simply create my own Zend_View and override what needed to be overriden. Also, he was very wise to tell me to look at Zend/View.php itself for guidance. That and some helpful messages from exceptions during testing.

Here's the initial implementation, for which all tests pass.

PLAIN TEXT

PHP:

// Custom view that reads in templates from the database and
// writes them to the filesystem
class Xmlteam_ZFView extends Zend_View_Abstract
{
private $_filter = array();
private $_file = null;
public function __construct($config = array())
{
parent::__construct($config);
}
/**
* Custom method to see if template is in the file system
* and then load it into memory, write out to the file system
* if it doesn't
*
* @param string $name The script name to precess
* @return string THe script output
*/
public function render($name)
{
$scriptPaths = $this->getScriptPaths();
$filename = $scriptPaths[0] . $name;
if (!file_exists($filename)) {
list($league, $tmp) = explode('-', $name);
list($templateType, $extension) = explode('.', $tmp);
$q = Doctrine_Query::create()
->select('t.*')
->from('Template t')
->where('t.league_short_name = ?', $league)
->andWhere('t.type = ?', $templateType);
$q->setHydrationMode(Doctrine_Core::HYDRATE_ARRAY);
$results = $q->execute();
if (count($results)> 0) {
file_put_contents($filename, $results[0]['content']);
}
}
// find the script file name using the parent private method
$this->_file = $this->_script($name);
unset($name); // remove $name from local scope
ob_start();
$this->_run($filename);
return $this->_filter(ob_get_clean()); // filter output
}
/**
* Applies the filter callback to a buffer.
*
* @param string $buffer The buffer contents.
* @return string The filtered buffer.
*/
private function _filter($buffer)
{
// loop through each filter class
foreach ($this->_filter as $name) {
// load and apply the filter class
$filter = $this->getFilter($name);
$buffer = call_user_func(array($filter, 'filter'), $buffer);
}
// done!
return $buffer;
}
/**
* Includes the view script in a scope with only public $this variables.
*
* @param string The view script to execute.
*/
protected function _run()
{
if ($this->_useViewStream && $this->useStreamWrapper()) {
include 'zend.view://' . func_get_arg(0);
} else {
include func_get_arg(0);
}
}
}

So, what did I learn from this process?

I needed to create my own private _file and _filter variables to match what exists in so that if I create any custom filters they can be applied to my custom view *and* to keep compatibility with existing code.
Because the _run method is protected AND abstract, I needed to implement my own _run method in my custom view, or else it would spit out errors. Even if it doesn't do anything special.

You can see that the logic in my render method is pretty much as I outlined before. I realize I will take a slight hit the first time we go to load a particular template. I'm assuming at some point I will want to run a test to see just how long it does take to pull in the template from the database and write it to the file system. I'm guessing this will not be a serious performance hit, but you never know. All those file_exists() calls can't be that good for performance,

I look forward to seeing other potential solutions to this problem

Essential Programming Books: “Building Scalable Web Sites”

Chris Hartjes — Fri, 28 May 2010 20:29:43 +0000

Like many old sk00l developers, I like the security blanket a bookshelf full of technical books gives me. Whenever I have a problem, I check to see if I can figure it out using the reference materials on hand. Just looking at my shelves. Since She Who Must Be Obeyed Around Here frowns on boxes constantly showing up at our house from various online book retailers, I usually only purchase books that I think are going to be good additions to the library.

Taking a quick peek at my bookcase, these are a few of the books that I consider essential reference guides for me:

The Pragmatic Programmer
Practices of an Agile Developer
Mastering Regular Expressions
Beautiful Code / Beautiful Architecture
Javascript: The Good Parts

I have more books, but those are the ones closest to my desk.

There is now a new book that has earned a spot on my bookcase, and should be in one of the slots closest to my desk. I am reading a borrowed copy of it, but I plan on rectifying that soon. "Building Scalable Web Sites" by Cal Henderson (he of Flickr and "Why I Hate Django fame) is that book.

I don't know how I can describe how awesome this book is in this blog. Just check out the topics in the table of contents:

Introduction
Web Application Architecture
Development Environment
i18n, L10n, and Unicode
Data Integrity and Security
Email
Remote Services
Bottlenecks
Scaling Web Applications
Statistics, Monitoring, and Alerting
APIs

Pardon my vulgarity, but that is pretty much every single fucking thing you need to worry about when building a web site that is going to be used by anyone other than you and your close circle of friends.

This book is old in internet time: published in 2006, meaning it was probably written in 2004-2005. A lot of technology has changed, but the principles themselves have not. Also, a lot of the code inside uses PHP for it's examples, but I really think this applies to any programming language that is stateless and/or promotes a "shared nothing" architecture. That means (as far as I'm concerned) PHP, Python and Ruby. It's very simple: scaling anything is difficult, but scaling something where there is information that needs to be shared between nodes is extremely difficult. The best way to use this book is to ignore the specific technologies being mentioned and focus on the ideas and practices that are being promoted. I mean, let's be brutally honest: Cal Henderson helped build one of the most massively scaled web sites, using a programming language at it's core that the hipster programmer crowd sneers at. Ignore his advice at your peril.

Go buy this book. Right now. You will not regret it.

It’s The Community, Stupid

Chris Hartjes — Thu, 27 May 2010 01:08:37 +0000

I had an awesome time at Tek-X in Chicago last week. It was worth the 8 hour drive to get to Chicago from my basement lair. Of course, it helped that the wait at the border was under 10 minutes both times. There were good talks, but even better *people*.

A programming language is only as good as the community that supports. By supporting it, I mean willing to get together several times a year for conferences and bust their asses to have people share interesting talks with everyone else. Look at Python and Ruby. Awesome languages to work with. But even more awesome are the conferences that serve as anchors for the community.

There seems to be lots of little regional Ruby conferences, which give the language itself a unique flavour in return. Of course, it helps that Ruby can be used quite easily outside the traditional web application building environment. I don't see so many regional Python conferences, just PyCon and DjangoCon both in the US and over in Europe. It could be that I'm not looking hard enough.

As for PHP, to be fair, it shows up at pretty much any open source web-related conference. OS Bridge. OSCON. Codemash. I could go on, but I am not in the conference-promotion business. I mean, why is there no Great Canadian PHP Conference? I know there was phpworks in Toronto back in the mid 2000's. It was my first conference I ever went to. But I'll tell you why there is no Great Canadian PHP Conference: there is no PHP community in Toronto.

Oh sure, there are tons of PHP jobs to be had in Toronto. Lots of code monkey positions to be filled. But the Toronto PHP User's group has been dormant since last year. I sent an email to the organizer telling him I wanted to help out at least 3 days ago. Haven't heard a damn thing back. Perhaps it is time to go around such a person and just do it myself.

See, without the PHP community I do not have a career. Once I took the plunge, submitted a talk, and got accepted (I gave a talk about what the PHP community could learn from Ruby on Rails) I found I had suddenly joined the PHP *community*. Instantly I had people asking me questions AND people willing to answer my questions. Like I was their long-lost buddy. That was an awesome feeling, let me tell you. But even more important were the people I met.

As a result of the community, I have found myself in the awesome position that every time I needed a job, it took less than a week to get one. It was a combination of my blogging and my work in making those connections in the community that put me in this position, but it is sure a nice feeling to be able to convince your nervous wife that we were not about to face a rough patch while I struggled to find work. So it's a no-brainer for me to continue to submit talks to conferences and try to attend even when I don't speak. It's about giving something back to the community that has helped me grow my career.

So don't just *use* your language of choice. Try and become part of that community. Doesn't matter if it's Python, Ruby, or good-old-solved-the-web-problem-first PHP. You'd be surprised what doors are opened up by your participation.

Off to TEK-X

Chris Hartjes — Mon, 17 May 2010 17:58:46 +0000

Tomorrow (May 18) I throw all my junk in the trunk of my trusty steed (a 2000 Ford Taurus that loves to chew up the highway miles) and hit the road for Chicago for TEK-X, the 10th edition of this conference. I have spoken at previous editions (is that the correct word?) of this conference and I'll be honest: I'm a bit bummed that I'm not speaking.

See, I normally only go to conferences when I speak. Why? Being away from the family is tough to arrange when you work from home. I've got two little girls, and they are used to Daddy being around to help out with stuff. Like taking them to day care, or picking them up from school. Making dinner. Helping with school lunches. Grocery shopping. I'm sure you get the picture. So to abandon the family to go to a conference requires lots of logistical work.

But damnit, I hadn't been to a conference since March of last year (the old PHP Quebec conference) I was determined not to get shut out. Luckily my boss agreed to foot the bill and so off I go. I'd love to meet any of my readers, and even sign paper copies of my book if you got a print-on-demand version. Hell, I don't even have one. So don't be intimidated by my size, appearance, or lack of knowledge on certain topics. Come and say hi. I'll the big, bald, grumpy Canadian with a pot-scrubber on his chin stomping around the conference.

Anyway, I wanted to talk about the sessions I'm looking forward to seeing. In no particular order, here they are:

Building Real-Time Applications with XMPP

I've known Travis for a while through the PHP community, and never seen him do a presentation. However, his numerous IM sessions helping me understand decorators in the context of Django and talking me through fixing totally busted Git commits lead me to one conclusion: he knows his shit so I should pay attention to what he has to say. The building of our next-gen fantasy sports gaming platform starts when I get back so I'm hoping he imparts some pearls of wisdom.

Continuous Inspection and Integration of PHP Projects

Being the only guy working on projects gets frustrating: nobody to share ideas with and also very hard to make the case for the types of tools and procedures that the TDD/BDD and continuous integration crowd advocates. I mean, all this work so Chris stops complaining about bugs slipping through the QA cycle? Besides, I always have a soft-spot for Ze Germans who are always at the PHP conferences.

Graphs, Edges & Nodes: Untangling the Social Web

I first met the presenter (Joel Perras) at PHP Quebec last year through the CakePHP community. Now that he's moved on to the Lithium project, I see his ego has grown to the point where he is okay giving presentations. Don't worry whippersnapper, I'll cut you down to size during this (probably awesome because it deals with stats and nodes and graphs and all this cool stuff I've been reading in "Programming Collective Intelligence") talk.

Now, I'm sure that I will be attending other sessions while I'm there. But those are the main ones I'm looking forward to seeing. We are spoiled for choice at this conference, and I am definitely looking forward to seeing old friends and making some new ones.

Is There A More Practical Approach To TDD?

Chris Hartjes — Tue, 30 Mar 2010 19:31:42 +0000

One of the things I (foolishly perhaps) promised myself when I started up a new project at work was that I was going to use Test Driven Development (or TDD for short). I advocated using a web application framework that supports good testing practices and discussed how it would be beneficial when trying to track down and solve bugs to have a set of tests. I ran through the impact of my horrible decision to use a framework without a good culture of testing in a previous project: fixing things became tedious as I could not run automated tests to verify that things were working properly.

But a funny thing has happened while building the new application. Sadly, there are no automated tests, and the question I've been asking myself is "other than being lazy as hell, why did you not write tests?". The answer I seem to have come up with (or justified is probably the better word) is "I don't see anything complicated in what I'm doing that I need to write a test for." Before you dismiss my thoughts on this, consider the architecture of what I've built:

We have a backend consisting of MySQL with two distinct databases on it: one containing raw stats for sporting events, the other summarized records about fantasy points accumulated by players. My thought was to make the database do all the work of crunching the numbers for me as a daily cron job and then the web front end only needs to do reads. With proper indexing of the tables, performance is at an acceptable level with a full season's set of test data. Sounds like a pretty decent strategy to me.

The scripts that collect the raw data and pre-calculate fantasy point totals are written in Python. The web site that displays the fantasy points info was done with Zend Framework. So what sort of tests should I have written for this. I've come around to the idea that you should write tests for things that are non-trivial. Then you get into the problem of deciding what is non-trivial:

Verify that point totals are being calculated correctly
Verify that when players are assigned to teams in our admin panel they actually end up, you know, being on the proper team

Every else seems to me to be, well, not worth testing. Make sure teams are sorted in order of total fantasy points? Database does that for me. Make sure list of players for a specific team contain expected players for a team? Um, database does that for me(?). I can verify that players are properly changing teams in the admin panel by hand. Of course, I shouldn't be testing things by hand, but I'm wondering if I'm either missing the point or have stumbled upon something here.

Am I missing something here? Am I doing it wrong? I do believe I need some tests, but only for the things that are not super-obvious. I'd appreciate people's thoughts on this. Maybe I just need someone else to look at it the app as a whole and say "we should be testing for the following things". The curse of the lone programmer maybe?

“U R Doin It Wrong” – Adventures with flexible forms in Zend Framework

Chris Hartjes — Fri, 19 Mar 2010 16:19:54 +0000

Zend_Form is a super-powerful, force-of-nature tool. By force-of-nature I mean it does all this crazy stuff, and you can see it doing it, but I am not alone in admitting that taming it sometimes is very difficult. When building tools to make form programatically you either severely limit peoples options or make it so flexible that there are multiple ways to get something done. Given the concept that Zend Framework "treats you like an adult" (I cannot find the blog post where I read this) it is not surprising that Zend_Form takes the flexible route.

Before I go any further, thanks (again) to @elazar and to Rob Allen aka @akrabat for helping me solve this particular problem.

Okay, so onto my problem. I was creating a page for a fantasy baseball draft application to process transaction requests. You could do one thing, and one thing only: make a request to add a free agent to your team and what player off your team you wanted to drop. Since I needed to locate form elements in specific places in the layout, I didn't do the usual < ?= $form ?> in my template, instead I created a bunch of setX methods, with X representing a specific form element. Then, in my templates I simply did < ?= $form->X ?> where X represents the specific element. Let me show you what I mean:

PLAIN TEXT

PHP:

"/baseball/league ?>/transactions/process" method="post">
= $this->transactionForm->teamId ?>
= $this->transactionForm->shortLeagueName ?>

                "100%">                    
                        
"50%" align="center">Players on your Team

"50%" align="center">Players Available

"center" valign="top">

                            = $this->transactionForm->players ?>
                        
"center" valign="top">

"freeAgentList">
                                = $this->transactionForm->freeAgents ?>

"submit" id="transactionFormSubmit" value="Request Selection"/>

"50%" align="center">Players on your Team	"50%" align="center">Players Available
"center" valign="top"> = $this->transactionForm->players ?>	"center" valign="top"> "freeAgentList"> = $this->transactionForm->freeAgents ?>

I did this figuring it would give me lots of flexibility. Then, the pain started.

I kept wondering why every time I validated the form, it kept coming back as true. I had a requirement that to have a successful transaction request, they had to select both a player to drop from their own team AND a free agent to add. I had put into the form validation that a free agent was required, but it never seemed to be triggered. Off to Stack Overflow I went to ask for help, along with pleas for help on Twitter. I had thought I was doing something subtly wrong, and I was right.

Here's the finished, working code. I will explain what I had been doing wrong. By the way, if you can think of a better way to do something of the more "hackish" stuff in there, I'd appreciate it.

PLAIN TEXT

PHP:

public function indexAction()
{
$form = new Baseball_Form_Transactions();
$options = array(
'teamId' => $this->teamId,
'position' => 'C',
'leagueShortName' => $this->league,
'status' => 0
);
$form->setMyPlayers($options);
$form->setFreeAgents($options);
$form->setTeamId($options);
$form->setShortLeagueName($options);
if ($this->getRequest()->isPost()) {
// This is hack to make sure we pull back the list of free agents for
// the player's position
$postData = $this->_request->getPost();
$player = Doctrine::getTable('Player')->find($postData['players']);
$options['position'] = $player['position'];
$form->setFreeAgents($options);
if ($form->isValid($this->_request->getPost())) {
$data = $form->getValues();
$leagueInfo = Doctrine::getTable('League')->findOneByShortName($data['shortLeagueName'])->toArray();
// Create the request top drop an existing player
$transactionInfo = array(
'league_id' => $leagueInfo['id'],
'team_id' => $data['teamId'],
'player_id' => $data['players'],
'type' => 'drop',
'target_team_id' => 0,
'transaction_date' => date('Y-m-d H:m:s'),
'shortLeagueName' => $data['shortLeagueName'],
'group_id' => uniqid()
);
$transaction = new Transaction();
$transaction->fromArray($transactionInfo);
$transaction->save();
// Now we do the request to add a player
$transactionInfo['team_id'] = 0;
$transactionInfo['player_id'] = $data['freeAgents'];
$transactionInfo['target_team_id'] = $data['teamId'];
$transactionInfo['type'] = 'add';
$transaction = new Transaction();
$transaction->fromArray($transactionInfo);
$transaction->save();
$this->_flashMessenger->addMessage('Added transaction');
}
}
$this->view->transactionForm = $form;
$this->view->messages = $this->_flashMessenger->getMessages();
$transaction = new Transaction();
$this->view->transactions = $transaction->byTeam($options);
}

The big mistake? I was not setting up all the form elements via my setX calls BEFORE I did the validation. Because I didn't, those elements didn't exist, and therefore the validation never got called. See, I told you my mistake was (a) dumb and (b) subtle.

I think I did the right thing with my method of creating the form elements outside of the init() method to give me the ability to layout things where I wanted them. I'm interested in finding out how other people have solved the same problem.

Expand your programming mind: filters in Lithium

Chris Hartjes — Tue, 16 Mar 2010 15:27:17 +0000

Out of the ashes of a severe personality clash in an open source PHP web application framework project rose a new framework proclaiming that it simply sucks less than all the others. Lithium, otherwise known as li3, is the latest PHP application framework to come onto the scene. I know what you're saying. *Yawn*.

As far as I can tell, Lithium is trying it's hardest to be fast, lightweight, and use all the features that PHP 5.3 has to offer. I am unable to use it at work for a variety of reasons (not stable, required PHP 5.3 only, Nate is always picking on me via IM) but I am more interested in the ideas that are coming out of it.

It is using all the newest hawtness in the PHP world: namespaces, closures, Phar, late static binding. I could go on, but probably most of these things mean nothing to you until you actually need them. In the framework world, namespaces are a big deal, an essential tool to avoiding collisions with 3rd party code you might want to integrate into your project. Closures are very familiar to those who've done work with Ruby or Javascript. Phar allows for some unarchiving on the fly of code, even potentially distributing your application as an archive that can be run. Late static binding is something I'm trying to comes to grips with, as I have either never come across a need for it or never realized that I did and have implemented a workaround for it not realizing there is a simpler solution.

None of these are what I want to talk about. I want to talk about something that I feel is a very underrated part of Lithium, the ability to define filters. This is a concept that you find in Aspect-oriented programming, and one that I imagine most programmers have never considered. Here's why I think it's a big deal.

Most frameworks are designed around an OOP paradigm. Yes, some mix them together (I'm looking at *you* CodeIgniter), but by and large you get the job done by extending on a base model / controller / helper / whatever to create new functionality. Sometimes this is not avoidable. But what AOP says is that there is another way, a way that Lithium has adopted as well.

Hence the creation of "filters". As far as I can tell (and I'm sure I will be jumped upon if I am wrong) the purpose of filters in Lithium is to allow you to add functionality without extending the class itself. When I saw that I immediately understood why that is so awesome.

The idea of callbacks is also very similar: if X happens, run code Y. A staple of jQuery, Rails and probably other projects I have forgotten to mention. The idea is still the same though. In Garrett Woodworth's presentation about Lithium to the Orange County PHP Users Group he goes over some solid examples of filters including:

automatic use of the XHProf for code profiling
automatic setting of parameters upon saving a pasted bit of code

It's also been used to automatically change string record ID's into a MongoDB ID and graceful failing of an integration test suite when an error occurs.

These filters remind me of behaviors in Rails (and in CakePHP as well) and makes me wonder if signals are the same thing in the Django world. All in all, this looks to me to be a better way to extend functionality than actually overriding existing methods or hacking at something deep inside a class. Figure out what functionality you want, figure out where it needs to be called, and add your filter.

People Who Make Me Feel Stupid: Ezra Zygmuntowicz

Chris Hartjes — Thu, 04 Mar 2010 14:00:47 +0000

This is the 4th out of 5 blog posts about programmers who I find make me feel stupid when I read what they write or hear them speak. Stupid because what they say is so obvious I cannot believe I missed it. See my thoughts on Geoffrey Grosenbach, Antirez and Rich Hickey.

Next up is another prominent member of the Ruby community, one that I feel truly deserves the label "Renaissance Programmer". He is Ezra Zygmuntowicz, co-founder of Engine Yard, probably the leader in helping people deploy Rails applications of all shapes and sizes. Ezra seems to have done it all, from Rails work, to Merb, to the Ruby VM Rubinus.

If I remember correctly, I first encountered Ezra and his work (and his awesome last name) during my Ruby on Rails research. Realizing that Rails was the dominate framework in that space, I wondered what the alternatives were. That lead me to Merb. Unfortunately at the time it was not well-documented, so I drifted into other things (like so many other times, I'm sensing a pattern here). Then I started hearing about the efforts to create an alternative to the standard Ruby virtual machine, with the goal of creating, I imagine, a faster Ruby environment.

Much as I cannot imagine writing my own programming language, I could not imagine creating a virtual machine based on running code in an already-established language. Then I saw this talk Ezra gave about Merb, Rubinus and the stack that Engine Yard uses. What blew me away was when he started explaining *how* he was going about implementing Rubinus. It made so much sense.

See, in the Ruby world you can use what they call Matz' Ruby Interpreter, or CRuby as a reference point. Since there is no official spec, the MRI is used. So if you want to create your own Ruby virtual machine, it's as simple as looking at how the MRI implements functionality and then copy it in your own VM. Repeat until your own virtual machine passes all the tests in the RubySpec project and bingo! You have a (hopefully as close to compatible with the MRI) virtual machine for running Ruby. It seems that YARV is a virtual machine (I believe it is a bytecode interpreter) that is included with the latest version of Ruby at this writing, 1.9.

So why does Ezra make me feel stupid: He has fully immersed himself in the Ruby world from the virtual machine to the language implementation to frameworks that sit on top of it. Like most of the people I talk about in this series, he also knows how to explain these things to people in such a way that you do not realize what awesome work he is doing.

I may not be doing anything with Ruby any more, but how can you not get interested in the nuts-and-bolts of a language and virtual machines in general when someone like Ezra explains it to you?!? In the PHP world, Facebook recently announced the release and open sourcing of Hip Hop for PHP. This project takes PHP code, parses it and generates C++ executables. This is a big deal for Facebook, who is the largest user of PHP out there. It lets them use approximately 50% fewer servers when delivering PHP-results. They did the same thing I talked about above: looked at how PHP implemented functions at the lowest level, and then figured out how to do it in C++. It's a very unique project, and obviously not for everyone. But again, an awesome case study on creating virtual machines / alternate runtimes for an existing programming language.

Sorting Relationship Results In Doctrine 1.2

Chris Hartjes — Thu, 04 Feb 2010 17:57:24 +0000

I've been building an admin panel for a work project dealing with fantasy sports, and one of the failings of the old version of the overall application was that, well, sometimes it didn't retain the desired display order of players grouped by position. Sometimes it worked, sometimes it didn't. A classic case of "software working by accident" maybe? So I've set out to fix that part of it.

I've been using Doctrine 1.2 for the project (integrated with Zend Framework), and I found it quite easy to setup the relationships I needed between my models. Oh, except for finding out that I really needed a field called 'id' in one table in order to make a relationship work properly. Sometimes convention triumphs over configuration.
So I thought to myself "I wonder if I can configure things so that when we're pulling in the related results, it is sorted?"

So I started digging around via search engine. Took me about an hour to find the solution. First, it took me half the time to dive deep enough to find out WHERE I can define the default sort order. Surprisingly, it was in an area that made total sense but I could not find before. Weird. Probably due to me not fulling understanding the API.

PLAIN TEXT

PHP:

class Team extends Doctrine_Record
{
public function setUp()
{
...
$this->hasMany('Player as Players', array(
'local' => 'team_id',
'foreign' => 'player_id',
'refClass' => 'PlayersTeams',
'orderBy' => 'FIELD(position, "C","1B", "2B" ,"3B", "SS", "OF", "P")'
));
}
}

Oh, what's all that other stuff? That's what took the other half of the hour to figure out. See, I couldn't use any sort of natural sorting order. I had a specific order that they needed to be displayed in. As usual StackOverflow came to my rescue. I'm pretty sure that what I am doing is MySQL-specific but I imagine you can figure it out for other RDBMS'.

So now when I pull in info about a Team, I get the associated Player records sorted to my heart's desire. Awesome. This does raise a question: how would you accomplish this sort of trick if you were using a non-relational database like CouchDB. Research for another day I guess.