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Subject: Re: [PHP-DEV] On how a little knowledge is completely useless.
From: ralph@smashlabs.com (Ralph Schindler)


On 9/17/10 12:49 PM, Stas Malyshev wrote:
> userspace) 2) adding syntax (probably can't be done in userspace unless
> somebody thinks of a clever way to do it).


I've thought of it, and I guess I'll give it a go, I could make this a 
proposal if it makes sense to.

The idea is to make the Zend Engine aware that annotations exist without 
the worry of what the syntax is.  Syntax can then be deferred to the 
consumer.  How to accomplish? Well:


* Zend Engine should have a new token T_ANNOTATION that is demarcated by 
an opening [ and a closing ] (with necessary escaping for \] along the 
way if need be) that should exists before PHP declarations (func, 
property, method, class, const, etc).  Multiple annotations per 
declaration are ok.


* Add new methods to Reflection APIs: getAnnotations() and 
getParsedAnnotations().


* Add a new extension called annotation responsible for registering and 
implementing annotation parsers:

   annotation_register_parser($name, AnnotationParser $p|$validcallback);

   ** and an interface for AnnotationParser

   interface AnnotationParser
   {
     public function tokenize($string); // array of tokens
     public function execute(array $tokens);
   }

   (if AnnotationParser is used, Reflection can "byte-code" cache the 
tokens from tokenize())


* Add real implementations of syntax:

   // class to handle proposed doctrine syntax, similar to c#
   class AnnotationAttributeParser { /** ... */ }

   // perhaps a simple key value based parser
   class AnnotationKeyValueParser { /** .. */ }

   // perhaps a PHP include parser
   class AnnotationPHPIncludeParser { /** .. */ }

* Usage:

   annotation_register_parser('doctrine', new AnnotationAttributeParser);

   // callbacks can be used as wel

   annotation_register_parser('zfservice', array('MyClass', 
'myCallbackMethod'));

How would this work?

   When Reflection<>::getParsedAnnotations() is called, it will check 
for a registered key in the annotation (of one does not exist, exception 
is thrown)..  code would look like this:

   [doctrine:ClassMap('foo' => 'bar', 'rest of c# nested syntax')]
   public $foo;

This also allows other frameworks to propose and use their own syntax 
that makes the most sense to them:

   [symfonyDi:arg1=Foo,arg2=Bar]
   public function setStuff(Foo $arg1, Bar $arg2) {...}

or

   [zendservice:param1=string;return=int]
   public function doFooForWebService() { /* .. */ return $someInt; }

you could even use url based annotations:

   annotation_register_parser('wordpress', 'parse_str');

   in code:

   [wordpress:first=value&arr[]=foo+bar&arr[]=baz]
   function wp_plugin_handle_something() {}


Since annotation formats and knowing annotations might be required are a 
requirement of the framework/system the consumer has adopted, that 
framework can specify the format of the string used inside the annotation.

Also, multiple annotations can be attached to various declarations, 
hence the getParsedAnnotations(), perhaps getParsedAnnotation($index) 
would be valid as well.

thoughts?
-ralph