The power of PHP annotations

Hannes de Jager php

I was quite intrigued when I learned a while back that PHP documentation comments are available via reflection. This is the first language where I’ve seen this. This means that given the following code:

class AnyClass {
   * @param string $s
  public function anyFunc($s) {
    // Any code

You can actually get a hold of the comment block above anyFunc from your PHP script:

function getComment() {
  $c = new ReflectionClass('AnyClass');
  $m = $c->getMethod('anyFunc');
  return $m->getDocComment();        

With a little parsing effort this effectively gives PHP what Java calls annotations and C# calls Attributes – A means to add meta data to your code that can be used in your logic. Not sure PHP have a name for this, but I’ll call it PHP annotations.

function getAnnotations() {
  $c = new ReflectionClass('AnyClass');
  $m = $c->getMethod('anyFunc');
  $s = $m->getDocComment();        
  $s = str_replace('/*', '', $s);
  $s = str_replace('*/', '', $s);
  $s = str_replace('*', '', $s);
  $aTags = explode('@', $s);
  return $aTags;

From this I was able to build a small little MVC framework that power-use these PHP annotations. For example here is a MVC controller action function:

 * @param code is required
 * @param name is required
 * @param query is required
 * @loadview stored-query-save
 * @ajaxify 
public function storedQuerySaveAction() {
  // At this point the framework made 
  // sure the HTTP request contains 
  // something in the code, name and 
  // query variables
  // When this action function 
  // returns the framework will 
  // render a view called stored-query-save
  // and the @ajaxify annotation will
  // cause the framework to add
  // some jQuery magic to the 
  // output to provide a better user
  // experience through the use
  // of ajax techniques.
Hannes de Jager
Software Builder