# Attributes support proposal

- Thread: https://externals.io/message/15989
- Original archive: https://news-web.php.net/php.internals/15989
- Started by Duncan McIntyre on 2005-04-18T12:19:55+00:00
- Messages: 8
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## #15989 — Duncan McIntyre — 2005-04-18T12:19:55+00:00

URL: https://externals.io/message/15989#15989

Hello,

I am playing around with an extension to the Zend Engine 2 to allow class 
properties and methods to be tagged with attributes. These attributes would 
then be accessible through the Reflection classes:

!---------- example -------------!
class Storable {

	[serializer:toString; persistent:true; ] public $date;

	function __construct() {
		$this->date = new CDate();
	}
	...
	...
}

$store = new Storable();

$rf = new ReflectionProperty("Storable","date");
$s = $rf->getAttributeValue("serializer");
if(!is_null($s) && method_exists($store, $s)) {
	$v = $store->date->$s();
} else {
	$v = $store->date;
}

echo "the value of the date property is $v";

!------------- /example -------------!

I would find the ability to set attributes extremely useful in building 
frameworks a la Ruby On Rails. 

Anyone think this is a good idea?

Duncan

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## #15990 — Wez Furlong — 2005-04-18T12:26:53+00:00

URL: https://externals.io/message/15989#15990 · In reply to: #15989

PHP has interfaces for this kind of thing, and they're clearer/cleaner
to use than the code you've posted (for this case at least).

It's also worth noting that the rendering of serialized data for an
object is usually better handled by the class of that object, not its
container.  It is fine, of course, for the container to stick that
serialized data somewhere else.

Placing attributes in the container for this seems like a lot of extra
work; you'd be repeating the same mantra for each class that contains
and instance of the child class.

From a technical viewpoint, how do these attributes affect the class? 
Are they simply no-ops that are tagged and made available via the
reflection API?  How does this really help improve PHP?  I know it
sounds cool, but so does recording phpdoc comments, and we decided to
not do that in the default case for performance reasons.  How are
these attributes much different from that?

I'm not against the idea per-se, I just can't see a really good reason
to justify it.

--Wez.


> Hello,
> 
> I am playing around with an extension to the Zend Engine 2 to allow class
> properties and methods to be tagged with attributes. These attributes would
> then be accessible through the Reflection classes:
> 
> !---------- example -------------!
> class Storable {
> 
>         [serializer:toString; persistent:true; ] public $date;
> 
>         function __construct() {
>                 $this->date = new CDate();
>         }
>         ...
>         ...
> }
> 
> $store = new Storable();
> 
> $rf = new ReflectionProperty("Storable","date");
> $s = $rf->getAttributeValue("serializer");
> if(!is_null($s) && method_exists($store, $s)) {
>         $v = $store->date->$s();
> } else {
>         $v = $store->date;
> }
> 
> echo "the value of the date property is $v";
> 
> !------------- /example -------------!
> 
> I would find the ability to set attributes extremely useful in building
> frameworks a la Ruby On Rails.
> 
> Anyone think this is a good idea?
> 
> Duncan

---

## #15991 — Hendy Irawan — 2005-04-18T12:36:37+00:00

URL: https://externals.io/message/15989#15991 · In reply to: #15989

> I am playing around with an extension to the Zend Engine 2 to allow class
> properties and methods to be tagged with attributes. These attributes would
> then be accessible through the Reflection classes:

Sorry guys to just jump in, but Duncan's idea is an EXCELLENT idea IMHO... :-)

Let's go beat up Ruby!!! ;-)

-- 
Hendy Irawan
http://www.gauldong.net
http://dev.gauldong.net

---

## #15992 — Hendy Irawan — 2005-04-18T13:17:43+00:00

URL: https://externals.io/message/15989#15992 · In reply to: #15990

> PHP has interfaces for this kind of thing, and they're clearer/cleaner
> to use than the code you've posted (for this case at least).
Yea, I completely agree.

> I'm not against the idea per-se, I just can't see a really good reason
> to justify it.
I hate to say this, but these ideas come from the "outside world":
- NUnit testing for .NET uses [Test] and [SetUp] attributes instead of
hardcoding method names (like test*, setUp, in xUnit test frameworks)
- ASP.NET uses WebMethod attribute for automatically exposing XML Web Services
- Aspect#.NET uses attributes for aspect oriented programming stuff

Speaking of AOP, I wonder if AOP features will ever be possible in PHP
(I guess this deserves another thread, maybe I'll have to search
archives first...)

-- 
Hendy Irawan
http://www.gauldong.net
http://dev.gauldong.net

---

## #15994 — George Schlossnagle — 2005-04-18T14:07:45+00:00

URL: https://externals.io/message/15989#15994 · In reply to: #15990

>
> From a technical viewpoint, how do these attributes affect the class?
> Are they simply no-ops that are tagged and made available via the
> reflection API?  How does this really help improve PHP?  I know it
> sounds cool, but so does recording phpdoc comments, and we decided to
> not do that in the default case for performance reasons.  How are
> these attributes much different from that?

A docblock parser would be nice though. :)

George

---

## #15996 — Derick Rethans — 2005-04-18T14:25:53+00:00

URL: https://externals.io/message/15989#15996 · In reply to: #15994

> 
> 
> > […]
> 
> A docblock parser would be nice though. :)

And we have one as far as I know.

Derick

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## #16000 — Timm Friebe — 2005-04-18T15:13:44+00:00

URL: https://externals.io/message/15989#16000 · In reply to: #15989

Hi,

[...]
> I am playing around with an extension to the Zend Engine 2 to 
> allow class properties and methods to be tagged with 
> attributes. These attributes would then be accessible through 
> the Reflection classes:

The PHP development team is usually against these kinds of OOP syntax sugar
additions, search Google / the archives for:

* Having IException as an interface instead of needing to 
  extend the builtin Exception class (php-internals)
* Static initializers (pear-dev)
* `with()` keyword (???)
* Namespaces (php-internals, zendengine2)
* Operator overloading (php-internals)
* throws clause (zendengine2)
* Passing `NULL` to typehints (php-internals)
* finally (php-internals)
* Return type hints (php-internals)
* self should reflect runtime class (php-internals)
* Automated getters/setters (php-internals)
(this list is by no means complete)

Having said that, how about implementing that in userland?

class Storable {
  #[serializer:toString; persistent:true;]
  public $date;
}

Extend (or wrap) the reflection classes and add:

  MyClass::getAnnotations()
  MyMethod::getAnnotations()
  MyProperty::getAnnotations()

In those, parse the sourcecode with ext/tokenizer and extract all comments
beginning with the string "#[", push them into a hashmap and return it.

It's not as slow as you might expect. Of course, it'll only work if you
don't use "#[" in any other comments:)

- Timm

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## #16002 — Sebastian Bergmann — 2005-04-18T15:33:22+00:00

URL: https://externals.io/message/15989#16002 · In reply to: #16000

Timm Friebe wrote:
> Extend (or wrap) the reflection classes and add:
> 
>   MyClass::getAnnotations()
>   MyMethod::getAnnotations()
>   MyProperty::getAnnotations()
> 
> In those, parse the sourcecode with ext/tokenizer and extract all 
> comments beginning with the string "#[", push them into a hashmap and 
> return it.

 I would like to see a PEAR (or even PECL) package that provides this
 functionality. I might even write it myself (given that I have a couple
 of long train rides coming up I will probably do this anyhow :-)

-- 
Sebastian Bergmann                      http://www.sebastian-bergmann.de/
GnuPG Key: 0xB85B5D69 / 27A7 2B14 09E4 98CD 6277 0E5B 6867 C514 B85B 5D69