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php

Attributes support proposal

php.internals

Duncan McIntyre

21 years ago

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

Wez Furlong

21 years ago

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.

On 4/18/05, Duncan McIntyre <duncan@calligram.co.uk> wrote:

Hendy Irawan

21 years ago

On 4/18/05, Wez Furlong <kingwez@gmail.com> wrote:

> 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

George Schlossnagle

21 years ago

On Apr 18, 2005, at 8:26 AM, Wez Furlong wrote:

>
> 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

Derick Rethans

21 years ago

On Mon, 18 Apr 2005, George Schlossnagle wrote:

>
> On Apr 18, 2005, at 8:26 AM, Wez Furlong wrote:
> >
> >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. :)

And we have one as far as I know.

Derick

Hendy Irawan

21 years ago

> 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

Timm Friebe

21 years ago

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

Sebastian Bergmann

21 years ago

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

Timm Friebe

21 years ago

Hi,

[...]

> 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 :-)

Come on, you don't need a long trainride for that.

http://sitten-polizei.de/php/annotations.php.txt

- Timm

Sebastian Bergmann

21 years ago

Timm Friebe wrote:

> Come on, you don't need a long trainride for that.

For the essence of it, no. But to make it "beautiful" ... we'll see. :-)

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

Sebastian Bergmann

21 years ago

Timm Friebe wrote:

> Come on, you don't need a long trainride for that.

I could not resist, initial code (no actual annotation parsing, yet!) is
here:

http://sebastian-bergmann.de/stuff/Annotation/Reflection/Annotation.phps
http://sebastian-bergmann.de/stuff/Annotation/Reflection/Class.phps
http://sebastian-bergmann.de/stuff/Annotation/Reflection/Method.phps
http://sebastian-bergmann.de/stuff/Annotation/Reflection/Property.phps
http://sebastian-bergmann.de/stuff/Annotation/Parser.phps
http://sebastian-bergmann.de/stuff/Annotation/test.phps

The only thing the code currently does is to extend the existing
Reflection API class and make them "annotation-aware".

The next step to be coded is the annotation parser which will be called
from the Annotation_Reflection_Class::__construct(),
Annotation_Reflection_Method::__construct(), and
Annotation_Reflection_Property::__construct() methods.

Since this is no longer on-topic on this list please reply via PM.

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