Thoughts and feedback about AOP

[lisachenko]

If you are using an AOP or have a plan to use it, please add a small comment here or just put a +1 ) I will be happy to see that this technique can be useful for you )
You can also provide an additional information about the usage (how you use it and where). I can put this information later on my site with hyper-link to your solution.

[JeyDotC]

Hello @lisachenko, here is a use case I've been thinking about:

Dependency injection

I've a proof of concept of dependency injection with Aura DI (Which I'll upload soon and obviously put a link here) if one's DI aspect is well designed, the backend library can be anything from AuraDI to Laravel to Symfony, etc.

Your classes would need to declare dependencies by just fulfilling the pointcuts configured in your aspect:

<?php
/**
* @ThisClassNeedsDI() !
*/
class MyClass {
    function __construct(SomeOtherClass $dependency){}
}

or

<?php
class MyClass {
    /**
    * @InjectSomethingHere(id="some_di_key") !
    */
    protected $iNeedAnInjection;
}

The advantages I see here are the proxies, nothing on reflection or things like that, just your dependency-resolving code injected in the right spots.

With the right aspects, GoAOP can even be the core for an IOC container :)

[lisachenko]

@JeyDotC Thank you for the feedback! Really interesting use case.

We can extend it by providing virtual composer packages, eg something/di-aware and real implementations for symfony2, zend that provide something/di-aware and build a bridge with an aspects to the concrete framework. BTW, I had the same idea earlier and wanted to rewrite lisachenko/warlock to be a bridge between SF2.3 DI )

[alekciy]

+1

[TheCelavi]

I have a contest of the problem which can be properly solved with AOP only. After research, I am stunned that PHP does not supports AOP in its core! AOP is MUST HAVE for PHP to compete with modern programming languages.

[lisachenko]

AOP is MUST HAVE for PHP to compete with modern programming languages.

Yes ) It would be cool, but at the moment there is no implementation for the core, however there was a try: http://code.google.com/p/yaxx/source/browse/trunk/php/zend_language_parser.y?r=2#314

So, only real solutions are: FLOW3 with AOP, JMSAopBundle for Symfony2, Ray.AOP, my framework and AOP-PHP extension (unfortunately, not compiling for PHP>=5.5). But we need our community to move AOP forward, because PHP is a great tool and we can use it power together with AOP.

Thank you for supporting AOP in PHP, @TheCelavi

[bgaillard]

Hi, we principaly use AOP to configure transactions around our service Layers.

This is a standard practive in Java and it works too using PHP / Go AOP.

It allows to have a clean service layer without the need to manually begin / commit / rollback transactions, so it prevents spaghetti code / transaction coding errors.

For example :

class UserService implements IUserService {

    /**
     * The Data Mapper used to manage users persistence.
     * 
     * @Inject
     * @var \Application\Dal\DataMapper\UserDataMapper
     */
    protected $userDataMapper;

    /**
     * {@inheritdoc}
     */
    public function save(User $user) {

        // Multiple database create / read / update operations inside one transaction...

    }
}

Then we define the following (simplified here) TransactionAspect class :

class TransactionAspect implements Aspect {

    /**
     * The Zend Database Adapter to be used to manage transactions to the database.
     *
     * @var \Zend\Db\Adapter\AdapterInterface
     */
    private $dbAdapter;

    /**
     * Method called around service functions which have to be transactional.
     *
     * @param \Go\Aop\Intercept\MethodInvocation $methodInvocation an object which represents the service method which
     *        is called.
     * 
     * @Around("execution(public Application\Service\Impl\*Service->create*(*)) || execution(public Application\Service\Impl\*Service->delete*(*)) || execution(public Application\Service\Impl\*Service->save*(*)) || execution(public Application\Service\Impl\*Service->update*(*))")
     * 
     * @throws \Exception if an exception is encountered in the wrapped service function.
     * 
     * @return mixed the return of the function associated to the join point.
     */
    public function around(MethodInvocation $methodInvocation) {

        $this -> dbAdapter -> getDriver() -> getConnection() -> beginTransaction();

        try {

            $ret = $methodInvocation -> proceed();
            $this -> dbAdapter -> getDriver() -> getConnection() -> commit();
            return $ret;

        } catch (\Exception $exception) {

            $this -> dbAdapter -> getDriver() -> getConnection() -> rollBack();
            throw $exception;

        }

}

We also used https://github.com/AOP-PHP/AOP the same way in one of our project. But as the project is not really maintained we're planning to abandon it by using Go AOP instead.

Sadly AOP-PHP is a C extension which seems to be hard to maintain (few developers produce good quality code in C or even understand the C language) and it does not work under Windows without modifications in the build scripts / sources.

So thanks @lisachenko for this great framework !

👍

[baptistepillot]

+1 I wrote my own AOP implementation, massively inspired by the techniques you used - thanks a lot -, into my framework. It allows me to design getters and setters in php, to write modular plugins without having to tell the core they may exist... I am convinced AOP is a must-have for high level programming languages now, a plus for huge structured applications.

Thanks a lot for your work.

[lisachenko]

Oh, thank you, @bgaillard and @baptistepillot! You just give me a feeling that my work is useful and I can continue development. Without feedback for many months my motivation to work on AOP were decreased to very low level. I even had a thoughts about is it really needed by developers or not.

So many developers think that AOP is not for "true" OOP programmers and their negative comments can not help me with building more transparent and flexible library. But I looking forward for AOP community that can work together and share thoughts and examples of the usage )

I'm also feel honored that my framework can be a replacement for AOP-PHP extension, because this means that Go! AOP framework is more stable and fast enough to be used in production without worrying about speed.

So, thanks a lot for supporting me with feedback! 👍

[bgaillard]

Hi @lisachenko,

Without feedback for many months my motivation to work on AOP were decreased to very low level. I even had a thoughts about is it really needed by developers or not.

I'm working with PHP since only 2 years now. I came from the Java world and when I started to code with PHP I had a lot of questions but few of the PHP developers I knew at the moment could respond to me. Questions like "How do you automatically manage transactions ?", "Argh, this peace of code is ugly, how do you work with your collegues now ?", "Is their any solid Dependency Injection framework available ?", "Do you use something like Checkstyle to verify coding standards", "How do you manage dependency versions ?" etc...

In my opinion PHP is maturing because several tools and best practices used to respond to those questions emerged the last 2 / 3 years (PSRs, composer, PHPUnit, CodeSniffer, PHP-DI, PhpDocumentor, etc...).

But we already had all those tools and practices in Java since 5 / 10 years (Maven, JUnit, Checkstyle, Spring, Javadoc, etc...) !

AOP is something well known by Java developers, but most PHP developers simply do no know it exists yet ! In my opinion AOP is an almost vital feature needed by a well written PHP web application but sadly PHP devs do not know it or how / where to use it :-(

So many developers think that AOP is not for "true" OOP programmers and their negative comments can not help me with building more transparent and flexible library. But I looking forward for AOP community that can work together and share thoughts and examples of the usage )

Our applications uses AOP only at few places in the code, I rarely saw an app which extensively used AOP. In my opinion AOP should be used for specific use cases only and it clearly not "breaks" OOP. It helps prevent spagetti / redondant peaces of code on large apps and it definitly helps to produce clean, readable and good quality code (for the sceptics see this article http://veerasundar.com/blog/2010/01/use-cases-of-aspect-oriented-programming).

This is perhaps what we have to explain more to gain much more traction from the PHP community.

Thanks again and please don't give up :-) !

[lisachenko]

AOP is something well known by Java developers, but most PHP developers simply do no know it exists yet !

Yes, unfortunately, it's true. But I can see increasing number of visits on go.aopphp.com as well as the number of repo cloning. And it's a good sign for me :)

@carlosgoce now doing a great job by writing an articles about the usage of AOP (Spanish language): http://blog.carlosgoce.com/simplifica-tus-transacciones-en-laravel-con-anotaciones-aop/ and
http://blog.carlosgoce.com/realizando-cache-con-aop-en-laravel-4/

In my opinion AOP should be used for specific use cases only and it clearly not "breaks" OOP. It helps prevent spagetti / redondant peaces of code on large apps and it definitly helps to produce clean, readable and good quality code (for the sceptics see this article http://veerasundar.com/blog/2010/01/use-cases-of-aspect-oriented-programming).

Entirely agree with you that AOP is a special tool for solving special issues with spaghetti code. And it's perfectly extend OOP with new techniques.

I will keep working on this project to make it better, faster and mature )

[JeyDotC]

Another possible usage could be a port of C#'s Insight Database which has a feature in which one can define an interface (namely a repositry) and it generates the implementation at runtime.

Go! AOP may provide a good way to implement it, is something to be discussed :)

[crisp-github]

Using it for logging now - thanks! Would like to know if there is a way to only consider methods defined in the file where an annotation is ? Or some way to achieve same. We don't want to log methods from base classes. Cheers!

[lisachenko]

@crisp-github can you provide your pointcut expression for logging? You can build any complex pointcuts with logical &&, || and ! operators. For example, mark a class with an annotation and then match only public methods in this class.

[markNZed]

@lisachenko thanks. Currently doing this:

public function isDeclaredInClass(MethodInvocation $invocation)
    {
        $obj        = $invocation->getThis();
        $class      = is_object($obj) ? get_class($obj) : $obj;
        $method     = $invocation->getMethod();
        $declaringClassName = $method->getDeclaringClass()->name;

        // If the method is not declared in the same class then we don't log it
        // reduced noise.
        $length = strlen($class);
        $match = (substr($declaringClassName, 0, $length) === $class);

        return $match; 
    }