Exceptions are and should be an integral part of any general purpose programming language. PHP introduced them long ago (with the release of PHP 5 or 5.1), but it still seems that many of the concepts are not fully understood or ignored by the community. This post aims to be a solid introduction to exception architecture, handling and testing. At the end of the post you should be able to know when to raise an exception and how it should look like.

He talks about situations when (and when not) to use exceptions, normalizing them for easier try/catch-ing and includes the exception class hierarchy, including the types pulled from the SPL. He shows examples (based on the Lithium framework's namespacing) how to create "namespaced exceptions" and how to use these in a bit of sample code. He also mentions the use of the custom error handling with the ErrorException as well as a quick look at testing these basic and custom exceptions correctly (PHPUnit-based tests).

For a new proof of concept application I'm building, I need both a simple web interface as well as some commandline tools. I decided to use Silex for the web interface and Cilex for the CLI tools, and opted for using Composer for installing these dependencies into my project. I ran into some issues with the custom project libraries I was building for this application however. Registering my custom namespace into Silex and Cilex didn't result in the classes being loaded for some reason. Composer helped me out though.

His solution involves letting Composer be the default autoloader for the application via an "autoloader" configuration option in the "composer.json" (that can also take a classmap option if you're not PSR-0 compliant, see here).

I know that there are a lot of posts now about namespaces in PHP 5.3. This is mine which is how I learnt how they work. [...] That is, namespaces allow us to: combine libraries with the same classnames, avoid very long classnames and organise our code easily. Note that namespaces do not just affect classes. They also affect functions and constants.

He starts with the basic namespace definition (using the "namespace" keyword), shows how to import another namespace with "use" and the use of the __NAMESPACE__ constant to determine what namespace you're operating in. More information on namespaces can be found in the PHP manual.

In this article I'll walk you through the "history of autoloading," from the older to the current PSR-0 standard autoloader approach found in many PHP frameworks such as Lithium, Symfony, Zend, etc. Then I will introduce you to the ClassLoader component from the Symfony2 project for PHP 5.3 which follows the PSR-0 standard.

He starts with a look at a basic "__autoload" function call that looks in a directory for libraries. Improving on that, he makes two methods for loading - one for controllers, the other for models - and a loader that splits on the "_" character and determines the path from there.

Even this isn't PSR-0, though, so he shows how using namespace information, you can load classes in a unified way. He shows how to implement this with a loader that's already well-developed and ready for use - the Symfony ClassLoader component. They show how to register namespaces, prefixes as well as use the APC functionality to manually store/fetch the APC version of the loaded file's opcodes.

As Drupal is in the process of considering how to restructure code to best leverage the PSR-0 standard, I figured it would be wise to take a quick survey of how some other major projects organize their code bases. This is not a complete rundown of every project, simply roughly comparable notes for those areas Drupal is currently discussing. I am posting it here in the hopes that it will be useful to more than just Drupal.

The projects he looked to for his examples were:

• CakePHP
• Symfony2
• Silex
• CodeIgniter
• Zend Framework 2
• Composer

If you have a closer look at the code, front.php has one input, the Request, and one output, the Response. Our framework class will follow this simple principle: the logic is about creating the Response associated with a Request. As the Symfony2 components requires PHP 5.3, let's create our very own namespace for our framework: Simplex.

He puts the main front controller in just the "Simplex" namespace but adds in others for the controllers and models. He also updates his Composer configuration to create some PSR-0 autoloading.

For [a chapter in my book on dependency injection] I am using Pimple, an incredibly small but effective dependency injection container. Easy to use, simple and effective documentation, just what I was looking for. I also noticed that Pimple supported the use of closures (or anonymous functions) as a way of storing a dependency. Then things got stupid.

He shares a bit of code showing how he added it to his bootstrap but was given a "cannot find class" error when he tried to use the tool. He walks through the steps he followed to track down the problem - looking closer at Pimple, investigating closures and, the ultimate problem, namespace scoping. He was missing a "" to start his namespace and closures work slightly differently:

So why does it behave differently inside closures? I am not 100% sure, but if I had to make an educated guess I would say that when trying to resolve namespaces inside a closure, the interpretor doesn't assume that it is already inside the global namespace, that it is in a namespace of it's own.

Namespaces were a long awaited feature in PHP. While many other important features were released with PHP 5, namespaces were not supported until version 5.3. This led to various techniques for emulating them which, though necessary, were messy and confusing. Although namespaces have been part of PHP for over a year now, such techniques still exist. Many developers simply don't know how to use proper namespaces in their code. In this article I will explain why namespaces are important and how you can use them in your own PHP code.

He starts off by talking about what namespaces are and how they can be used to segment up applications, especially larger ones, into more manageable chunks. Basic code is included showing how to implement a namespace, referencing items inside a namespace, the "use" keyword and the __NAMESPACE__ magic variable.

The inclusion of namespace support within PHP 5.3 effectively brought the need for gripes and workarounds to a halt, however adoption of this exciting new feature has seemed surprisingly slow in the more than two years since its release. [...] The utility of this new feature is simply undeniable. Therefore I thought it would be worthwhile to offer a formal introduction to namespaces for the benefit of those PHP developers who haven't yet had the opportunity to investigate the topic.

He starts by introducing the concept of a "namespace" as a sort of container for your code, providing separation that prevents errors like the infamous "cannot redeclare class" issue. He includes examples of PHP's namespace syntax to split out two "Account" classes into two different sections. Using them is as easy as referring to them by their namespaced "path" or using something like the "use" keyword to reassign it to another name.

It wasn't until years later that certain best practices had emerged and the prolific usage of require_once/include_once throughout large bodies of code had started drying up. Even after autoloading had been adopted by larger more visible projects, a common patten had yet to emerge. [...] Fast-forward to today, and we see that this standard for autoloading has agreed upon by a large number of projects and has come to be named the "PSR-0 autoloading standard".

He covers some of the things we (the development community) have learned about autoloading and resources in our applications. He talks about the classmap tool that Matthew Weier O'Phinney developed (and some of its downfalls) as well as a move into PHP namespacing that has helped to make some of the "namespacing" based on class names obsolete. He's noticed a pattern in namespacing already - a self-contained structure that provides more of a "drop in" solution and how that's handled in the code.