Annotations are a really helpful feature in present-day development. An annotation is a special form of syntactic metadata that can be added to source code elements such as classes, methods, properties and parameters. They do not affect the program semantic directly, but can be used by tools and libraries to handle such annotated code in a certain way.

He notes that, as of right now, PHP doesn't naively support anything like this but that there are additional libraries that can be used to augment the standard PHP performance and use them (like a feature in PHPUnit with @assert and @test). He also go through several of the other libraries that make it possible including Addendum, FLOW3 and the XP-Framework.

At my company, we typically organize our test case classes into high-level groups such as unit and functional. Method-level group annotations are inconvenient for us because we'd need to annotate every method of every test case class.

He includes an example of their use - commenting a testing class and running it through the phpunit command line tool with a call to the testing group's name.

In Stephan's post:

Porting JavaDoc comments to PHP was one of the best things, that ever happened to to PHP4. But like in Java 4, the DocBlocks in PHP evolved from plain documentation to a feature that adds meta information to classes, methods, properties and variables. IDEs, like Zend Studio, use the @var tag to enable type hinting for method return values, which would not possible without the DocBlock, as PHP is a dynamic languages.

And from Frank:

In part three of his wishlist for PHP 6 Stephan wrote that he would like to see annotations built into PHP 6 directly. I disagree with him about that. Annotations can be done in userland, without any problems. He already gave some examples of projects that accomplished this task. But if you look at them you see that every project has a different solution on how to implement annotations for PHP which leads to the problem that if you use different projects in your own application you have to handle all their ways of treating annotations. Annoying, isn't it?

• In this new post, Frank Kleine takes things a step further and talks about the same kind of type hinting but for more types - including arrays and objects. Examples of how he'd expect things to work followed.
• The other post is from Stephan Schmidt again and varies slightly off into the world of Namespaces to be included in PHP6 along with the use of annotations.