annotate.php

This project provides Java style annotations for PHP.

Example

Let's assume we're writing a web request router. We could use annotations to supply the routes and which method is associated.

Defining an annotation

<?php

require_once('Annotate.php');

/**
 * @AnnotationTarget(AnnotatedElementType::METHOD)
 */
class Route extends Annotation {}

Using the annotation above we can now define a controller and apply the annotation.

<?php

require_once('Annotate.php');

class Controller {
	/**
	 * @Route('/')
	 */
	function home() {}
	
	/**
	 * @Route('/login')
	 */
	function login() {}
}

Using an annotation

Now that we have defined our annotation and applied it to our controller we can define our web request router.

<?php

require_once('Annotate.php');

class RequestRouter {
	function process($path) {
		$reflect = new AnnotatedReflectionClass('Controller');
        $obj = $reflect->newInstance();
        foreach ($reflect->getMethods() as $method) {
            $route = $method->getAnnotation('Route');
            if ($route->value() == $path) {
                $method->invoke($obj);
                break;
            }
        }
	}
}

This is obviously a rudimentary example from the perspective of our RequestRouter, but it shows how the @Route annotation can be put to use.

Annotations with multiple values

By default all annotations have a single value called value. Annotations also allow you to define your own values if a single value is not enough.

<?php

require_once('Annotate.php');

/**
 * @AnnotationTarget(AnnotatedElementType::METHOD)
 */
class Route extends Annotation {
	public $path;
	public $method;
	
	public function __construct($path = null, $method = null) {
        $this->path = $path;
        $this->method = $method;
    }

    public function path() {
        return $this->path;
    }

    public function method() {
        return $this->method;
    }
}

Now our @Route will allow us to specify a path as well as a request method.

<?php

require_once('Annotate.php');

class Controller {
	/**
	 * @Route('/', 'GET')
	 */
	function home() {}
	
	/**
	 * @Route('/login', 'GET')
	 */
	function login() {}
	
	/**
	 * @Route('/login/auth', 'POST')
	 */
	function loginAuth() {}
}

Now our home and login controller methods indicate that they support a GET request method, while loginAuth supports POST. We would obviously need to update our RequestRouter accordingly.

Named parameters

If you are providing all the parameters that your annotation expects, or if all the parameters you supply are in the correct order you don't need to do anything special. If you only want to pass some of your parameters however you will need to use named parameters.

<?php

require_once('Annotate.php');

class Controller {
	/**
	 * This route ignores the method parameter
	 * @Route('/foo')
	 */
	function home() {}
	
	/**
	 * This route ignores the path parameter so we have to specify that the
	 * parameter we are passing is meant to be used as the method value.
	 * This is obviously pointless, but for the sake of example...
	 * @Route(method='GET')
	 */
	function bar() {}
}

API Documentation

AnnotatedReflectionClass

This class extends ReflectionClass and introduces the following methods:

• getAnnotations
• getAnnotation($annotationClass)
• hasAnnotation($annotationClass)

AnnotatedReflectionMethod

This class extends ReflectionMethod and introduces the following methods:

• getAnnotations
• getAnnotation($annotationClass)
• hasAnnotation($annotationClass)

AnnotatedReflectionProperty

This class extends ReflectionProperty and introduces the following methods:

• getAnnotations
• getAnnotation($annotationClass)
• hasAnnotation($annotationClass)

Annotation

You must extend this class anytime you define your own custom annotation.

@AnnotationTarget

This supplied annotation is used to specify the target of annotations. It takes one of the values from AnnotatedElementType as it's value.

AnnotatedElementType

You can specify a target to annotation classes and limit what element type they pertain to. The value of the @AnnotationTarget is one of these values:

• ANNOTATION_TYPE - Annotation type declaration
• CONSTRUCTOR - Constructor declaration
• METHOD - Method declaration
• PROPERTY - Property declaration (includes constants)
• TYPE - Class (including annotation type), or interface declaration