Alexander Lisachenkolisachenko.it@gmail.com

Getting rid of duplicate code: weaving aspects in PHP with the help of Go! AOP library

Speaker profile

Lisachenko Alexander

• Senior Web Architect at Alpari

• Symfony2 enthusiast: nearly a dozen internal services based on Symfony2, including primary site alpari.ru(CDN, Varnish+ESI, Twig, Assetic, ~60 submodules, ~20 bundles)

• Machine programming;

• Structured programming;

• Procedure programming;

• Module programming;

• Object-oriented programming;

• < new high-level paradigm >

The evolution of programming

Key elements: classes, objects.

Principles: abstraction, encapsulation, inheritance and polymorphism.

Good old OOP…

The principle of single responsibility

The principle of single responsibility

The principle of single responsibility

Authorization...

Logging...

Exception handling...

All because of crosscutting concerns that permeates all of the code, like a skewer.

This code can not be placed in separate classes, and is everywhere:

• caching;

• logging;

• exception handling;

• authorization;

• transactionality.

Why is this so?

The clinical diagnosis of typical application: <censored>-code

• unsuitable for reuse;

• difficult to understand the original purpose of the class, tangled logic, cyclomatic complexity;

• more likely to make a mistake and forget to write "boilerplate" code;

• copying of the code, the violation of DRY.

What do we have in the end?

AOP to the rescue!

AOP to the rescue!

Aspect-Oriented Programming (AOP)

• AOP - programming technique in the class paradigm, based on the concept of aspect - a block of code that encapsulates the crosscutting logic in the class.

AOP History

•1974 – the principle of division of responsibility

•1990 – AOP researchе

• Composition Filters

• Subject-Oriented Programming

• Adaptive Programming

• 1997 - Aspect-Oriented Programming (report on the European Conference on OOP)

• 2001 – AspectJ AOP framework development

Basic concepts of AOP

• Aspect - the module or class implementing crosscutting concerns. Aspect changes the behavior of the rest of the code, using advice in joinpoints identified by some pointcut.

• Advice - action taken by an aspect at a particular join point. Different types of advice include "around," "before" and "after" advice.

Basic concepts of AOP

• Join point — a point during the execution of a program, such as the execution of a method or the handling of an exception.

• Pointcut — set of join point. Pointcut determines if it is suitable join point to the advice given.

• Introduction — changing the structure of the class and / or change the inheritance hierarchy to add aspect functionality in foreign code.

Basic concepts of AOP

Basic advice types

• Before - advice that executes before a join point, but which does not have the ability to prevent execution flow proceeding to the join point.

• After - advice to be executed after a join point completes normally.

• Around - advice that surrounds a join point such as a method invocation. Around advice responsible for choosing whether to proceed to the join point or to shortcut the advised method execution by returning its own return value or throwing an exception.

Basic advice types

Before

Before

After

After Throwing

Place for AOP in PHP

AOP complements existing technology into a single entity:• Dependency injection (IoC, DIC)• Abstraction of services (yaml, xml, php)• Aspect-Oriented Programming

Place for AOP in PHP

• Dependency injection• Abstraction of services• Aspect-Oriented Programming

Current implementation of AOP

Promising solutions:

• AOP-PHP

• JMSAopBundle

• TYPO3 Flow AOP component

Cemetery:

• PHPAspect

• Aspect-Oriented PHP

• AspectPHP

Go! library

The basic idea is not new - replace a class with a similar class-decorator implementation.

Key points:

• Static analysis of classes before loading them into memory (php-token-reflection, ApiGen)ядро

• Change the class hierarchy "on the fly"

• Modification of source code for the class at the time of class load, caching

Go! library

• Does not use PHP-extensions, written entirely in PHP itself;

• Does not require the DI-container for spoofing services with proxy objects;

• Can intercept methods in final classes, final methods, and static methods;

• Can intercept access to public and protected properties;

• Clean code is generated, it is convenient to debug classes and aspects with XDebug

Class source code

Aspect class

The result of running...

Processed code of the class

A good example is the best sermon

A good example is the best sermon

Caching with aspect example

What is expected?

• Pointcut parser (look at FLOW3)

• Introduction — add traits and interfaces to classes

• Caching array of advices in shared-memory — no need to check anything at runtime (hello, serialization of Closure)

• Init joinpoints — replace all «new» expressions with custom joinpoints

• Maximum performance :)

Thank you!

Questions?https://github.com/lisachenko/go-aop-php

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Link to the library: