DaveDevelopment::Dave Marshall

Sometime last year, I, along with quite a few others, was asked to review one of
Packt Publishing’s new books, Zend Framework 1.8 Web Application Development, written by Keith Pope. They sent me a copy, which was very good of them and although it’s taken me ages to finish and get round to writing this review, that’s not a true reflection of how good the book was, I’m just a very busy/lazy person! So lazy, that I did in fact say I’d have it done in two weeks, which turned into 4 months.

Packt asked if I’d be interested in reviewing the book, so watch this space, I’ll be back in a couple of weeks with a review.

My Post dated 15/10/2009

Introduction

Design, develop, and deploy feature-rich PHP web applications with this MVC framework

That is the books strap line, and it does exactly what it says on the tin. The bulk of the book actually takes you through the design, development, testing and deployment of a real world example application, called the Storefront. The book claims that it is written for PHP web developers that are either using or looking to start using the Zend Framework and that a basic knowledge of Object Oriented design would be helpful. While you might be able to manage without any OOD experience, I’d say you definitely need some to get the most out of this book, as the second chapter digs right under the hood of the Frameworks MVC architecture. My personal experience was that I got to learn all the things I haven’t had time to learn, I’ve been using the Framework for a couple of years now, always appreciating, but not always understanding what it was doing for me.

MVC Architecture

The first chapter gives you a brief overview of creating an MVC application in the Zend Framework, experienced users of the Framework will probably want to gloss over this part, whereas people looking to start using the framework should take their time and take things in. The next chapter is when I really started to enjoy the book. Each component of the MVC architecture is presented as it’s own topic, with each component getting a breakdown of Design Patterns/theory, default settings/configuration, usage and finally customisation.

The chapter is well put together and considering the amount of information portrayed, is not overwhelming.

Storefront Application

The rest of the book provides the information you need about the framework around a real world example application, called StoreFront, which is a basic e-commerce application. I should point out that I didn’t code the application as I went, if I’m reading I like to read, but where appropriate I have used the book as a reference when updating my existing Zend Framework applications.

The best thing about these chapters though, is some of the design theory you pick up on the way, that isn’t directly relevant to the Zend Framework, but can be applied to any framework out there. Best practices such as Fat Models, Composition, Fluent interfaces are all explained in detail, along with relevant and realistic examples. Further more, the applications MVC separation is excellent, taken in context (it might be a little overkill for the example application, but is there to show you the methods).

After taking you through the creation of the application, the book then takes you into optimisation and testing. The optimisation takes you though some general PHP optimisation techniques, but then ploughs into techniques like a transparent abstract cache that is applied to the models. Testing is carried out with the trusty PHPUnit, along with the frameworks extension of the library Zend_Test and the book goes on to integrate the test suites with apache ant (why not phing) and phpundercontrol.

Conclusion

In conclusion, I thought this book was an excellent read and I plan to follow it through again when I build my next ZF app (I have two good ideas in the pipeline). Find out more or and buy it!. Thanks to Packt for sending me a copy!

If anybody missed it, the last few days has seen plenty of buzz around a new proposal on how to solve the problem with URL shorteners. I kind of got lost in all the different methods and proposals people are discussing, suggesting or implementing, but I went ahead and added some simple logic to lnkd.in, to do a HTTP HEAD request to the given URL, looking for headers in a couple of the formats suggested. I figured that was going to get out of date pretty quickly, so I modified it to use the RevCanonical API, seems to work pretty well, returning a rev=canonical url wherever possible.

I also contributed a basic bit of code to Rob Allen’s Shorter Links plugin for wordpress, allowing users to specifying a base url, davedevelopment.co.uk isn’t all that good for short URLs. Just need to upgrade the plugin and decide on a short domain for my blog now.

Update: registerd daved.in, works a treat

After seeing a response to a thread on Hacker News, I thought I’d have a crack at making a simple little URL shortener with CodeIgniter. I’ve never used the framework before and it was a nice quick little app to implement and get a feel for things. It’s not quite worthy of competing with Bit.ly or Tinyurl.com, there’s no checking for spam urls etc, but if you want to take a look, the source code is available, as is a live demo at lnkd.in.

Not so long ago I was working on a little project using the django framework and was looking for a simple nested set implementation, I found one that was good enough for my needs on djangosnippets.org. I thought this was pretty cool, and realised we didn’t have a one stop shop for Zend Framework code snippets. Symfony and CakePHP also have dedicated sites for this. I’m aware of generic snippets sites and pastebin sites, but I thought it’d be another good learning opportunity to build my own with the Zend Framework, for the Zend Framework.

I’ve ended up implementing a pretty simple site, ZFSnippets. The current basic implementation makes use of:

• Zend_Auth
• Zend_Config
• Zend_Controller
• Zend_Db
• Zend_Feed
• Zend_Form
• Zend_Layout

• Zend_Mail
• Zend_OpenId
• Zend_Paginator
• Zend_Registry
• Zend_Session
• Zend_View

There are plenty of things I’d like to implement (and fix;)), but will have to see if I find anytime:

• A site search engine using Zend_Search_Lucene
• More flexible posting, probably using wiki style markup
• Version history for all snippets
• Moving to a stackoverflow.com style, trust model, allowing regular users to collaborate, edit and update snippets.
• Forgot my password link
• Contextual error handling and descriptions
• Accurate scoring/ranking, based on complex calculations.

I did actually spend quite a bit of time looking at markup libraries, coupled with HTMLPurifier, but it seemed like too much effort to start with, so I opted for a method of splitting the source code using hashes like pastie.

I like the idea of having a go with Zend_Search_Lucene, probably adding particular snippets to a queue for indexing whenever somebody posts one or comments on one.

Having built the site, I’m actually struggling to think of what might go on there. Helpers seem like an obvious one, but without building large, complex Zend Framework application, I don’t have much need for custom code, the framework does the leg work for me. Nevermind, if you think it might be any use to you, head on over there and have a browse around, although it’s a little low on content at the minute, or maybe subscribe to the feed and keep your eye out for anything interesting.

Before my much needed Holiday, a colleague of mine asked for my input on a funny issue he was having. The root of the problem was that our production server is still running PHP 5.1.2, where as most of us run 5.2.x on our development and test machines. My problem was that what I was seeing didn’t make sense. The following portion of code is a simple reproduction of the code my colleague was using, running fine on PHP 5.2.x, but causing a fatal error on the production server running 5.1.2, an attribute access violation.

<?php
class BankAccount
{
    protected $balance;

    public function __construct($balance)
    {
        $this->balance = $balance;
    }

    public function __toString()
    {
        return 'Balance: ' . $this->balance;
    }

    public function debit($debit)
    {
        $this->balance -= $credit;
    }

    public function credit($credit)
    {
        $this->balance += $credit;
    }
}

class SavingsAccount extends BankAccount
{
    public function __construct(BankAccount $parent)
    {
        $this->balance = $parent->balance;
    }
}

$first = new BankAccount(1.00);
$second = new SavingsAccount($first);

echo $second, PHP_EOL; // Balance: 1

It turns out that PHP’s visibility restrictions are on a class level, rather than an instance level, and the fatal error was actually due to a bug in 5.1.x.

The visibility of a property or method can be defined by prefixing the declaration with the keywords: public, protected or private. Public declared items can be accessed everywhere. Protected limits access to inherited and parent classes (and to the class that defines the item). Private limits visibility only to the class that defines the item.

This bemused me, as it would appear to me there is no point having a protected operator at all. Suppose I am a lowly programmer given the BankAccount Class above as an API I can use but not change. I have a data access object that returns BankAccount objects too, which I also can’t touch. For reasons unknown to me, but probably to try and create some encapsulation so they can log transactions via the credit and debit methods, the original developer decided that I shouldn’t be able to directly access the balance attribute, but I want to.

<?php

//$myAccount = $dao->getAccount(123);
$myAccount = new BankAccount(1.00);
echo $myAccount, PHP_EOL; // Balance: 1

class WorkAround extends BankAccount
{
    public static function setBalance(BankAccount $acc, $balance)
    {
        $acc->balance = $balance;
    }
}

WorkAround::setBalance($myAccount, 1000000.00);
echo $myAccount, PHP_EOL; // Balance: 1000000

This just doesn’t seem right to me. Don’t get me wrong, I appreciate there needs to be some level of responsibility taken by developers to not do this kind of thing. My colleague writes a lot of Java, in which this is also the expected behaviour with the protected visibility, hence why he set out on this path, so it seemed right to him. Because of this I embarked on a little research to determine how other languages implement visibility.

A very quick and non-extensive bit of research led me to believe that Python doesn’t have visibility as I know it, and C# has protected and internal, but neither work the way I’d like. Ruby has the closest to what I desire in the form of instance variables, but I’m sure there’s plenty I’ve missed.

class BankAccount
    def initialize(bal)
        @balance = bal
    end

    def debit(debit)
        @balance -= debit
    end

    def credit(credit)
        @balance += credit
    end

    def to_s
        "Balance: %d" % @balance
    end
end

class SavingsAccount < BankAccount
    def setBalance(acc, bal)
        # This wont work - we cant access acc.balance
        # acc.balance = balance;
    end

    def bonusCredit(credit)
        # just to prove a sub class can access
        # the instance variable
        @balance += credit + 1
    end
end

first = BankAccount.new(42);
second = SavingsAccount.new(1);

second.setBalance(first, 5000000);
second.bonusCredit(10);

print first  # Balance: 42
print second # Balance: 12 

It worries me sometimes when I come across things like this that I blatantly should know and understand properly. Cheers JC.