On Fri, Apr 22, 2016 at 3:07 AM, Dmitry Stogov <dmi...@zend.com> wrote:
>
>
> On 04/22/2016 04:05 AM, guilhermebla...@gmail.com wrote:
>
> Hi Dmitry,
>
> As a previous suggester of metadata information built-in into PHP, and
> also one of developers of the most used metadata library written in PHP, I
> understand this feature implementation requires several design decisions
> and also a good understanding of specific situations users may require.
>
> While I am a strong supporter of a more robust solution, this is already a
> good start.
> A few things I'd like to ask for my own understanding and also suggestions
> too:
>
> 1- I understand you took a minimalistic approach towards a "dumb"
> implementation for attributes (when I mean "dumb", the idea here is towards
> a non-OO approach). Can you explain your motivations towards this approach?
>
> I see two distinct approaches of implementation for this feature. Both of
> them have some common demands, like lazy initialization of metadata. Here
> they are:
>
> - Simplistic approach, which lets consumers of the feature do all the work
> related to validation, assertion of valid keys, values, etc
> This does not invalidate the ability to leverage of some features that a
> more robust implementation demands.
>
> - Robust approach: language takes the burden of instantiating complex
> structures, validating, assertion of valid keys, values, if this complex
> structure is allowed to be instantiated in that given class, method, etc.
>
>
> I didn't exactly understand what do you suggest.
> If you are talking about Attribute objects initialization during
> compilation - this is just not possible from implementation point of view.
> Now attributes may be stored in opcache SHM and relive request boundary.
> Objects can't relive requests.
>
I know that object instances are not cross-requests. Explicitly, I
mentioned that both approaches require lazy-initialization (which means,
whenever you call getAttributes() or getAttribute()).
What I mentioning is that your approach is basically a new key/value syntax
that are used specifically for Attributes. We could easily turn this into a
more robust approach if instead of defining key/value pairs, we instantiate
objects or call functions. You already demonstrated interest to support
<<ORM\Entity>> reusing the imports (which is our biggest headache in
Doctrine Annotations), so why not issue constructor or function calls
there? That would simplify the work needed for consumers and also add room
for later improvements.
So basically in this example:
use Doctrine\ORM;
<<ORM\Entity("user")>>
class User {}
$reflClass = new \ReflectionClass("User");
var_dump($reflClass->getAttributes());
We'd be changing from this:
array(1) {
["Doctrine\ORM\Entity"]=>
array(1) {
[0]=>
string(4) "user"
}
}
Into this:
array(1) {
["Doctrine\ORM\Entity"]=>
object(Doctrine\ORM\Entity)#1 (1) {
["tableName"]=>
string(4) "user"
}
}
>
> 1- Your approach is basically defining an array. Could you explain your
> line of thinking on why you didn't consider a syntax like the one below?
>
> <["key" => "value"]>
> class Foo {}
>
> I didn't try to invite new syntax. Just completely took it from HHVM.
>
My idea was based on your current proposal, which is basically a way to
define key/value pairs.
If you decide to go minimalistic, that is probably my best line of thinking.
>
>
>
> 2- I see that you added support over functions, classes, constants and
> properties. According to the RFC, getAttributes() was added over
> ReflectionFunction. Is there a reason why support was not added to methods
> (ReflectionMethod extends ReflectionFunctionAbstract, which was not
> mentioned on RFC)? Any reason to not support it in function/method
> parameters?
>
> ReflectionMethod is a child of ReflectinFunction, so it's supported.
>
Attributes are allowed for the same entities as doc-comments (they are not
> allowed for parameters)
>
I was asking if there was a purpose to not support Attributes over
ReflectionParameter. Example:
class Foo {
public function bar(<<Qux>> Bar $bar) : bool {
// ...
}
}
$reflClass = new \ReflectionClas("Foo");
$reflMethod = $reflClass->getMethod("bar");
$reflParameter = $reflMethod->getParameters()[0];
var_dump($reflParameter->getAttributes());
>
>
>
> 3- Did you put any thought on inheritance? What I mentioned in comment #1
> is even smaller than what you implemented in RFC.
> Assuming you keep the RFC approach, did you consider support overrides,
> inherit, etc?
>
>
> In my opinion, attributes don't have to be inherited.
> If you think differently - please explain your point.
>
Of source I can.
A simple case would be to increate visibility of the inherited property. It
was declared in a parent class as protected, but now you want public, and
you still want to keep all parent defined Attributes.
Another example is like we do in Doctrine. We support a callback system
which we named as lifetime callbacks. Pre-persist is one of them, which is
called every time a given Entity is about to be persisted into DB. When
you're dealing with inheritance, you can potentially override the method
content and you still want to trigger the same operation as if it was
untouched. Example:
use Doctrine\ORM;
trait Timestampable {
protected $created;
protected $updated;
<<ORM\PrePersist>>
public function prePersist() {
$this->created = $this->updated = new \DateTime("now");
}
<<ORM\PreUpdate>>
public function preUpdate() {
$this->updated = new \DateTime("now");
}
}
<<ORM\Entity>>
class User {
use Timestampable;
public function prePersist() {
// Add my custom logic
}
}
The implication is that through a simplistic approach, inheriting (or
overriding) is not clear and I can't figure it out an easy way to achieve
that.
Now if we go towards calling a function or class constructor like I
mentioned before, then we could easily build structures like __Inherit,
__Override, etc.
>
> 4- I understand that a more robust attribute solution would be required to
> achieve this, but one of the biggest advantages of AOP is the ability to
> perform custom logic before, after or around... However, I don't know if
> any kind of triggers came in your head or are planned as a future RFC.
> Let me highlight one example: Every time a class, property or method is
> called that is annotated as <<deprecated>>, I would like to issue an
> E_USER_DEPRECATED warning. A trigger-like solution would be required. Did
> this concept came to your mind?
>
> This is not a subject of this RFC.
> Attributes provides a storage for metadata, but don't define how to use
> them.
> Especially, for your use-case:
> 1) it's possible to create preprocessor that embeds corresponding
> trigger_error() call
> 2) it's possible to write a PHP extension that plugs-into compiler chain
> and checks <<deprecated>> attribute for each compiles function, then sets
> ZEND_ACC_DEPRECATED flag
> 3) It's also possible to override DO_FCALL opcodes and perform checks
> there (this is inefficient)
>
>
With this simplistic approach, I agree there's 0 value into considering
this.
However, taking a more robust approach would potentially open this
possibility through a simpler extension.
> Thanks. Dmitry.
>
>
>
>
>
> Regards,
>
> On Thu, Apr 21, 2016 at 7:44 PM, Dmitry Stogov <dmi...@zend.com> wrote:
>
>>
>>
>> On 04/22/2016 02:16 AM, Dominic Grostate wrote:
>>
>>>
>>> This is amazing. It would actually allow us to implement our automated
>>> assertions ourselves, as opposed to requiring it within the language.
>>>
>>> this was the idea - to give a good tool instead of implementing every
>> possible use-case in the language.
>>
>> Could it also support references?
>>>
>>> <<sanitize(&$a)>>
>>> function foo($a) {
>>>
>>> }
>>>
>>> yes. "&$a" is a valid PHP expression.
>>
>> If you plan to use this, I would appreciate, if you to build the patched
>> PHP and try it.
>> The early we find problems the better feature we will get at the end.
>>
>> Thanks. Dmitry.
>>
>>
>> On 21 Apr 2016 10:13 p.m., "Dmitry Stogov" < <dmi...@zend.com>
>>> dmi...@zend.com <mailto: <dmi...@zend.com>dmi...@zend.com>> wrote:
>>>
>>> Hi,
>>>
>>>
>>> I would like to present an RFC proposing support for native
>>> annotation.
>>>
>>> The naming, syntax and behavior are mostly influenced by HHVM
>>> Hack, but not exactly the same.
>>>
>>> The most interesting difference is an ability to use arbitrary PHP
>>> expressions as attribute values.
>>>
>>> These expressions are not evaluated, but stored as Abstract Syntax
>>> Trees, and later may be accessed (node by node) in PHP extensions,
>>> preprocessors and PHP scripts their selves. I think this ability
>>> may be useful for "Design By Contract", other formal verification
>>> systems, Aspect Oriented Programming, etc
>>>
>>>
>>> https://wiki.php.net/rfc/attributes
>>>
>>>
>>> Note that this approach is going to be native, in contrast to
>>> doc-comment approach that uses not well defined syntax, and even
>>> not parsed by PHP itself.
>>>
>>>
>>> Additional ideas, endorsement and criticism are welcome.
>>>
>>>
>>> Thanks. Dmitry.
>>>
>>>
>>
>
>
> --
> Guilherme Blanco
> Lead Architect at E-Block
>
>
>
--
Guilherme Blanco
Lead Architect at E-Block
