[PHP Development] A complete collection of PHP resources collected and compiled by foreign programmers, collected and compiled from abroad

[PHP Development] A complete list of PHP resources collected and compiled by foreign programmers, collected and compiled abroad

A list of PHP resources initiated and maintained by ziadoz on Github, including: libraries, frameworks, Templates, security, code analysis, logs, third-party libraries, configuration tools, web tools, books, e-books, classic blog posts, etc.

Dependency Management

Dependency and package management library

Composer/Packagist: a package and dependency manager
Composer Installers: A multi-framework Composer library installer
Pickle: A PHP extension installer

Other dependency management

Other related dependency management

Satis: a static Composer repository generator
Composition: A library that checks the Composer environment at runtime
Version: Semantic version parsing and comparison library
NameSpacer - A library that converts underscores into namespaces
Patch Installer - A library for installing patches using Composer
Composer Checker - Tool to verify Composer configuration

Frame

Web development framework

Symfony2 - a framework composed of independent components
Zend Framework 2 - Another framework composed of independent components
Laravel 4 - Another PHP framework
Aura PHP - a framework for independent components
Yii2 - Another PHP framework
Nette - Another framework composed of individual components
PPI Framework 2 - an interoperability framework
Phalcon - a framework implemented through C extensions

Other frameworks

Other web development frameworks

Symfony CMF - Content management framework for creating custom CMS
Knp RAD Bundle - Rapid Application (RAD) package for Symfony 2

Framework Component

Independent components from web development frameworks

Symfony2 Components -Symfony2 components
Zend Framework 2 Components -ZF2 Components
Aura Components -PHP5.4 component package
Hoa Project - Another PHP component package

Micro-framework

Microframework and Routing

Silex - a micro-framework based on Symfony2 components
Slim - Another simple micro framework
Bullet PHP - A micro-framework for building REST APIs
Fast Route - Fast routing library
Pux - Another fast routing library

Other microframeworks

Other related micro-frameworks and routing

Silex Skeleton -Silex project structure
Silex Web Profiler -Silex web debugging toolbar
Stack - Silex/Symfony stackable middleware library
Slim Skeleton -Slim architecture
Slim View -Slim’s custom view collection
Slim Middleware - Slim’s custom middleware collection

Template

Libraries and tools for templating and lexical analysis

Twig - a comprehensive template language
Twig Cache Extension - A template fragment caching library for Twig
Mustache - a PHP implementation of the Mustache template language
Phly Mustache - Another PHP implementation of the Mustache template language
MtHaml - A PHP implementation of HAML template language
PHPTAL - A PHP implementation of the TAL template language
Plates - a native PHP template library
Lex - a lightweight template parser

Static Site Generator

Preprocessing tools to generate the content of web pages.

Sculpin - Tool to convert Markdown and Twig to static HTML
Phrozn - Another tool to convert Textile, Markdown and Twig to HTML

HTTP

Libraries for HTTP and website scraping

Guzzle - A comprehensive HTTP client
Buzz - Another HTTP client
Requests - a simple HTTP library
HTTPFul - a chained HTTP library
Goutte - a simple web crawler
PHP VCR - Library for recording and replaying HTTP requests

URL

Library for parsing URLs

Purl - a URL processing library
PHP Domain Parser - a local prefix parsing library

Email

Library for sending and parsing emails

SwiftMailer - An email solution
PHPMailer - Another email solution
Fetch - an IMAP library
Email Reply Parser - an email reply parsing library
Stampie - Mail service library, inferior to SendGrid, PostMark, MailGun and Mandrill.
CssToInlineStyles - A library for inlining CSS in email templates

File

File processing and MIME type detection library

Gaufrette - a file system abstraction layer
Flysystem - Another file system abstraction layer
Canal - A library for detecting Internet media types
Apache MIME Types - A library for parsing Apache MIME types
Ferret - A MIME detection library
Hoa Mime - Another MIME detection library
Lurker - a resource tracking library
PHP File Locator - A library for locating files in large projects
PHP FFmpeg - A library for FFmpeg video packaging.
CSV - A CSV data processing library

Streams Stream

Library for processing streams

Streamer - an object-oriented stream packaging library

Dependency Injection

Library that implements the dependency injection design pattern

Pimple - a small dependency injection container
Auryn - Another dependency injection container
Orno Di - Another scalable dependency injection container
PHP DI - a dependency injection implemented using annotations
Acclimate - A common interface for dependency injection containers and service location

Image Image

Library for processing images

Imagine - an image processing library
PHP Image Workshop -Another image processing library
Intervention Image - Another image processing library
GIF Frame Extractor - a library for extracting GIF animation frame information
GIF Creator - A library for creating GIF animations from multiple images
Image With Text - A library for embedding text in images
Color Extractor - A library for extracting colors from images

Testing Test

Library for testing code and generating test data

PHPUnit - a unit testing framework
DBUnit - PHPUnit’s database testing library
ParaTest - PHPUnit’s parallel testing library
PHPSpec - Unit testing library based on function point design
Codeception - a full stack testing framework
AspectMock - PHPUnit/ Codeception simulation framework.
Atoum - a simple testing library
Mockery - a mock object library for testing
Phake - Another mock object library for testing
Prophecy - a highly optional simulation framework
Faker - a fake data generation library
Samsui - Another pseudo data generation library
Alice - an expressive generation library
Behat - a Behavior Driven Development (BDD) testing framework
Pho - a behavior-driven development testing framework
Mink -Web Acceptance Test
HTTP Mock - A library that simulates HTTP requests in unit tests
VFS Stream - A wrapper for virtual file system streams for testing
VFS - Another virtual file system for testing
Locust - A modern load testing library written in Python

Continuous Integration Continuous Integration

Continuously integrated libraries and applications

Travis CI - a continuous integration platform
PHPCI - an open source continuous integration platform for PHP
Sismo - a continuous testing service library
Jenkins is a continuous integration platform supported by PHP
JoliCi - A Docker-powered continuous integration client written in PHP

Documentation Document

Library for generating project documentation

Sami - an API documentation generator
APIGen - Another API documentation generator
PHP Documentor 2 - an API documentation generator
phpDox - a documentation generator for PHP projects (not limited to API documentation)

Security

Library for generating secure random numbers, encrypting data, and scanning for vulnerabilities

HTML Purifier - a standards-compliant HTML filter
RandomLib - A library for generating random numbers and strings
True Random - a library for generating random numbers using www.random.org
SecurityMultiTool - a PHP security library
PHPSecLib - a pure PHP secure communication library
TCrypto - A simple key-value encryption repository
PHP IDS - A structured PHP security layer
PHP SSH - An experimental object-oriented SSH wrapper library
IniScan - A library for scanning PHP INI file security
SensioLabs Security Check - A web tool that provides security recommendations for checking Composer dependencies
Zed - An integrated web application penetration testing tool

Passwords

Libraries and tools for handling and storing passwords

Password Compat - A new compatibility library for PHP5.5 password functions
phpass - A portable password hashing framework
PHP Password Lib - A library for generating and verifying passwords
Password Policy - A password policy library for PHP and JavaScript
Password Validator - A library for verifying and upgrading password hashes
Zxcvbn PHP - A realistic PHP password strength estimation library based on Zxcvbn JS

Code Analysis Code Analysis

Tools to analyze, parse and process libraries of your code base

PHP Parser - A PHP parser written in PHP
PHPPHP - a PHP virtual machine implemented by PHP
PHPSandbox - a PHP sandbox environment
Dissect - a collection of lexical and syntactic analysis tools
PHP Mess Detector - A library that scans for code defects, suboptimal code, unused parameters, and more.
PHP Code Sniffer - A library that detects PHP, CSS and JS code standards conflicts
PHPCPD - A library for detecting copied and pasted code
PHP Analyser - A library that analyzes PHP code to find defects and errors
PHP CS Fixer - A coding standards library
PHP Manipulator - A library for analyzing and modifying PHP source code
PHP Metrics - a static measurement library
PHP Refactoring Browser - A command line toolset for refactoring PHP code
UBench - A simple micro-benchmarking library
Athletic - an annotation-based benchmarking library
Mondrian - Use code analysis tools using graph theory
Scrutinizer - a web tool for reviewing PHP code
PHPLOC - A tool to quickly measure the size of PHP projects
xHprof - Another PHP profiling tool
PHPCcheckstyle - A tool to help adhere to specific coding conventions.

Debugging

Libraries and tools for debugging code

xDebug - A tool for debugging and analyzing PHP
PHP Debug Bar - A debugging toolbar
PHP Console - a web debugging console
Barbushin PHP Console - Another web debugging console using Google Chrome
PHPDBG - An interactive PHP debugger
Tracy - A simple error detection, logging and time measurement library

Build Tools Build Tools

Project building and automation tools

Go - a simple PHP build tool
Bob - A simple project automation tool
Phake - a PHP clone library
Box - A tool for building PHAR files
Phing - A PHP project build system inspired by Apache Ant

Task Runners Task Runners

Library for automatically running tasks

Task - A pure PHP task runner inspired by Grunt and Gulp
Robo - An object-oriented configured PHP task runner
Bldr - A PHP task runner built on Symfony components

Navigation

Tools for building navigation structures

KnpMenu - a menu library
Cartographer - a sitemap generation library

Asset Management Resource Management

Tools to manage, compress and minimize web site resources

Assetic - a pipeline library for resource management
Pipe - Another pipeline library for resource management
Munee - a resource optimization library
JShrink - a JavaScript minimization library
Puli - A library for detecting absolute paths to resources

Geolocation location

A library for geocoding addresses and using latitude and longitude.

GeoCoder - a geocoding library
GeoTools - a library related to geographical tools
PHPGeo - a simple geography library
GeoJSON - an implementation of geographical JSON

Date and Time Date and Time

Library for handling dates and times

Carbon - A simple date and time API extension
ExpressiveDate - Another date and time API extension
CalendR - a calendar management library

Event event

Library for time-driven or non-blocking event loop implementation

React - an event-driven non-blocking I/O library
Rx.PHP - a reactive extension library
Ratchet - a web socket library
Hoa WebSocket - Another web socket library
Hoa EventSource - an event source library
Evenement - an event distribution library
FuelPHP Event - Another event distribution library

Logging log

Library for generating and processing log files

Monolog - a comprehensive logging tool
KLogger - an easy-to-use PSR-3 compatible logging class

E-commerce E-commerce

Libraries and applications for processing payments and building online e-commerce stores

OmniPay - A framework hybrid library for multi-gateway payment processing
Payum - a payment abstraction library
Sylius - an open source e-commerce solution
Thelia - Another open source e-commerce solution
Money - A PHP implementation of Fowler’s money model
Sebastian Money - Another library for handling monetary values
Swap - an exchange rate library

PDF

Libraries and software for processing PDF files

Snappy - a PDF and image generator library
WKHTMLToPDF - A tool to convert HTML to PDF

Database database

Database interaction library using object-relational mapping (ORM) or data mapping technology

Doctrine - a comprehensive DBAL and ORM
Doctrine Extensions - a collection of Doctrine behavioral extensions
Propel - A fast ORM, migration library and query builder
Eloquent -Laravel 4 ORM
Baum - an Eloquent nested set implementation
Spot2 - a MySQL ORM mapper
RedBean - A lightweight, low-configuration ORM
Pomm - a PostgreSQL object model manager
ProxyManager - A toolset for generating proxy objects for data mapping

Migrations

Library to help manage database schemas and migrations

PHPMig - Another migration management library
Phinx - Another database migration management library
Migrations - a migration management library
Doctrine Migrations - a Doctrine migration library

NoSQL

Libraries for handling NoSQL backends

MongoQB - A MongoDB query building library
Monga - a MongoDB abstraction library
Predis - a fully functional Redis library

Queue Queue

Library for handling events and task queues

Pheanstalk - a Beanstalkd client library
PHP AMQP - A pure PHP AMQP library
Thumper - a RabbitMQ pattern library
Bernard - a multi-backend abstraction library

Search Search

Libraries and software that index and perform queries on data

ElasticSearch PHP - ElasticSearch’s official client library
Elastica - ElasticSearch client library
Solarium - Solr client library
SphinxQL query builder - Query library for Sphinx search engine

Command Line command line

Libraries for building command line tools

Boris - A Micro PHP REPL
PsySH - Another Micro PHP REPL
Pecan - an event-driven and non-blocking kernel
GetOpt - A command line selection parser
OptParse - Another command line selection parser
Commando - Another simple command line selection parser
GetOptionKit - Another command line options parser
Cron Expression - Library to calculate cron run date
ShellWrap - A simple command line wrapping library
Hoa Console - Another command line library
Shunt - A library for running command lines in parallel on multiple remote machines
Cilex - A micro-framework for building command line tools

Authentication

Library that implements authentication

Sentry - A hybrid authentication and authorization framework library
Sentry Social - A social network authentication library
Opauth - a multi-channel authentication framework
OAuth2 - An OAuth2 authentication service, resource server and client library
OAuth2 Server - Another OAuth2 server implementation
PHP oAuthLib - Another OAuth library
TwitterOAuth - A Twitter OAuth library
TwitterSDK - A fully tested Twitter SDK
Haw - A Hawk HTTP authentication library
HybridAuth - an open source social login library

Markup mark

Library for handling tags

Decoda - a lightweight tag parsing library
PHP Markdown - a Markdown parser
CommonMark PHP - a Markdown parser that fully supports CommonMark spec
Dflydev Markdown - Another Markdown parser
Parsedown - Another Markdown parser
Ciconia - Another Markdown parser that supports Github Markdown style
Cebe Markdown - A fast and extensible Markdown parser
HTML5 PHP - An HTML5 parsing and serialization library

Strings string

Library for parsing and processing strings

ANSI to HTML5 - ANSI to HTML5 conversion library
Patchwork UTF-8 - A portable library for processing UTF-8 strings
Hoa String - Another UTF-8 string library
Stringy - A string processing library with multi-byte support
Color Jizz - a library for processing and converting colors
UUID - Library for generating UUIDs
Slugify - a library that converts strings to slugs
Urlify - A URLify.jsPHP channel for Django
Text - a text processing library
SQL Formatter - a library for formatting SQL statements
UA Parser - A library for parsing user agent strings

Numbers Numbers

Library for processing numbers

Numbers PHP - library for processing numbers
Math - a library for processing large numbers
ByteUnits - Library for parsing, formatting and converting byte units in binary and metric systems
PHP Units of Measure - A library for unit of measurement conversion
PHP Conversion - Another library for unit of measurement conversion
LibPhoneNumber for PHP - PHP implementation library for Google phone number processing

Filtering and Validation

Library for filtering and validating data

Filterus - A simple PHP filtering library
Respect Validate - a simple validation library
Valitron - Another validation library
Upload - A library that handles file upload and verification
DMS Filter - a comment filtering library
MetaYaml - A schema validation library that supports YAML, JSON and XML
ISO-codes - Library for validating various ISO and ZIP encodings (IBAN, SWIFT/BIC, BBAN, VAT, SSN, UKNIN)

REST and API

Libraries and web tools for developing REST-ful APIs

Apigility - An API builder built with Zend Framework 2
Hateoas - a HOATEOAS REST web service library
HAL - A Hypertext Application Language (HAL) building library
Negotiation - a content negotiation library
Drest - A library that exposes Doctrine entities as REST resource nodes
Restler - A lightweight framework that exposes PHP methods as RESTful web API

Caching caching

Library for caching data

Alternative PHP Cache (APC) - Turn on PHP pseudo code caching
Cache - a caching library (Doctrine part)
Stash - Another caching library

Data structure and storage

Libraries that implement data structures and storage techniques

Ardent - a data structure library
PHP Collections - A simple collection library
Serializer - A library for serializing and deserializing data
PHP Object Storage - an object storage library
Fractal - A library for converting complex data structures into JSON output
Totem - A library for managing and exchanging sets of item data
PINQ - A PHP real-time Linq library
JsonMapper - A library that maps embedded JSON structures to PHP classes

Notifications

Library for handling notification software

Nod - a notification library (Growl, etc.)
Notificato - A library for handling push notifications
Notification Pusher - an independent library for device push notifications
Notificator - a lightweight notification library

Deployment deployment

Project deployment library

Pomander - a PHP application deployment tool
Rocketeer - a fast and simple deployer in the PHP world
Envoy - A tool to run SSH tasks with PHP
Plum - a deployment library

Internationalization and Localization

Internationalization (I18n) and localization (L10n)

Aura.Intl

Third Party API

Libraries for accessing third-party APIs

Amazon Web Service SDK - PHP AWS SDK official library
S3 Stream Wrapper -Amazon S3 stream packaging library
Stripe -Stripe official PHP library
Campaign Monitor -Campaign Monitor official PHP library
Digital Ocean -Digital Ocean API interface library
Github - Github API interactive library
PHP Github API - Another Github API interaction library
Twitter OAuth -Twitter OAuth workflow interaction library
Twitter REST - Twitter REST API interaction library
Dropbox SDK - The official PHP Dropbox SDK library.
Dropbox SDK - Dropbox SDK official PHP library
Twilio - The official Twilio PHP REST API.
Twilio - Twilio official PHP REST API
Mailgun The official Mailgun PHP API.
Mailgun Mailgun official PHP REST API

Extensions Extensions

Help the group build a PHP extension library

Zephir - a compiled language used to develop PHP extensions and is between PHP and C++
PHP CPP - A C++ library for developing PHP extensions

Miscellaneous

Useful libraries and tools not in the categories above

Spork - a library that handles forking
JSON Lint - A JSON lint tool
JSONPCallbackValidator - A library for validating JSONP callbacks
Pagerfanta - a paging library
Ruler - A simple stateless production environment rule engine.
LiteCQRS - A CQRS (Command Query Responsibility Separation) library
Sslurp - A library that reduces SSL processing
PHP Option an optional type library
Metrics - A simple metrics API library
Sabre VObject - A library for parsing VCard and iCalendar objects
Annotations - an annotation library (Doctrine part)
Whoops - a good error handling library
Finite - A simple PHP finite state machine
LadyBug - a dumper library
Procrastinator - a library for running time-consuming tasks
Compose - a function combination library
SuperClosure - A library that allows closure serialization
Jumper - a remote service execution library
Underscore - A PHP implementation of the Underscore JS library
PHP PassBook - An iOS PassBook PHP library
PHP Expression - a PHP expression language
RMT - A library for writing versions and publishing software
Wise - a configuration manager
Opengraph - an open library
Essence - a library for extracting web media
Embera - an Oembed consumption library
Graphviz - a graphics library
Monad PHP A simple Monad library
Flux - a regular expression building library
Patchwork - a function library that redefines users
Galapagos - Language Switch Evolution
Design Patterns PHP - A design pattern repository implemented in PHP
PHPCR - A PHP implementation of Java Content Repository (JCR)
Functional PHP - A functional programming library
ClassPreloader - a library that optimizes automatic loading
Lib Country - a library of country and region data
Lib Accessor - a library that simplifies access
PHPStack - A TCP/IP stack concept written in PHP
Nmap - An Nmap PHP wrapper
Code Mover - a library for moving code
Iter - A library that provides iteration primitives using generators
Lambda PHP - A Lambda calculation parser in PHP
Country List - List of all countries with name and ISO 3166-1 encoding
PHP-GPIO - Library for GPIO pins of Raspberry PI
print_o - An object graph visualizer
Alias - a category name library

Software software

Create software for a development environment

PHP installation

Tools to help install and manage PHP on your computer

HomeBrew - an OSX package manager
HomeBrew PHP - A HomeBrew PHP channel
PHP OSX - A PHP installer for OSX
PHP Brew - A PHP version management and installer
PHP Env - Another PHP version manager
PHP Switch - Another PHP version manager
PHP Build - Another PHP version installer
VirtPHP - A tool to create and manage independent PHP environments

Development Environment Development Environment

Software and tools for creating sandbox development environments

Vagrant - a portable development environment tool
Ansible - a very simple orchestration framework
Puppet - a server automation framework and application
PuPHPet - a web tool for building a virtual machine for PHP development
Protobox - Another web tool for building a virtual machine for PHP development
Phansible - a web tool that uses Ansible to build a PHP development virtual machine

Virtual Machines Virtual Machine

Related PHP virtual machine

HipHop PHP - PHP virtual machine, runtime and JIT produced by Facebook
HippyVM - Another PHP virtual machine
Hack - A HHVM programming language for seamless operation with PHP

IDE Integrated Development Environment

Integrated development environment supporting PHP

Netbeans - an IDE that supports PHP and HTML5
Eclipse for PHP Developers - A PHP IDE based on the Eclipse platform
PhpStorm - A commercial PHP IDE

Web Applications Web Applications

Web-based applications and tools

3V4L an online PHP shell
DBV - a database version control application
PHP Queue - An application for managing backend queues
Composer as a Service - Tool to download the Composer package as a zip file
MailCatcher - a web tool to capture and view emails

Resources Resources

Various resources to improve your PHP development skills and knowledge, such as books, websites, articles

PHP website

Useful websites related to PHP

PHP The Right Way - A quick guide to PHP best practices
PHP Best Practices - A PHP best practice guide
PHP Weekly - A PHP news weekly
PHP Security - A PHP Security Guide
PHP FIG - PHP Framework Interaction Group
PHP UG - A website that helps users locate the nearest PHP User Group (UG)
Seven PHP - A website where members of the PHP community are interviewed
Nomad PHP - an online PHP learning resource
PHP Mentoring - Peer-to-peer PHP mentoring organization

Other Websites Other Websites

Useful websites related to web development

The Open Web Application Security Project (OWASP) - an open software security community
WebSec IO - a web security community resource
Web Advent - A calendar for web developers
Semantic Versioning - A website that parses semantic versions
Atlassian Git Tutorials - a Git tutorial series
Hg Init - a Mercurial tutorial series
Servers for Hackers - A newsletter about server management

PHP Books

Very good books related to PHP

Scaling PHP Applications - An e-book by Steve Corona on scaling PHP applications
The Grumpy Programmer’s Guide to Building Testable PHP Applications - A book about building testable PHP applications by Chris Hartjes
Grumpy PHPUnit - A book by Chris Hartjes about using PHPUnit for unit testing
Mastering Object-Orientated PHP - A book about PHP object-oriented by Brandon Savage
Signaling PHP - A book by Cal Evans on capturing PCNTL signals in CLI scripts
Securing PHP: Core Concepts - A book by Chris Cornutt on common PHP security terms and practices
Modernising Legacy Applications in PHP - A book by Paul M. Jones about modernizing legacy PHP applications

Other books

Books related to general computing and web development

The Linux Command Line -A book about the Linux command line by William Shotts
Understanding Computation - a book about computing theory by Tom Stuart
The Tangled Web — Securing Web Applications - A book about web application security by Michal Zalewski
Elasticsearch: The Definitive Guide - A guide to working with Elasticsearch by Clinton Cormley and Zachary Tong
Eloquent JavaScript - a book about JavaScript programming by Marijin Haverbeke
Vagrant Cookbook-A book about creating a Vagrant environment by Erika Heidi
Pro Git - A book about Git by Scott Chacon and Ben Straub

PHP Video

Very good videos related to PHP

Taking PHP Seriously - from Facebook Keith Adams talks about the advantages of PHP
PHP Town Hall - A casual PHP podcast with Ben Edmunds and Phil Sturgeon
Programming with Anthony Anthony Ferrara’s video series

PHP Reading

PHP related reading materials

Create Your Own PHP Framework - A series of articles by Fabien Potencier on how to create your own PHP framework
Seven Ways to Screw Up BCrypt - An article about correcting BCrypt implementation
Preventing CSRF Attacks - An article on organizing CSRF attacks
Don’t Worry About BREACH - An article about BREACH attacks and CSRF tokens
On PHP 5.3, Lamda Functions and Closures - an article about lambda functions and closures
Use Env - An article about using unix environment help
Composer Primer - Composer Elementary
Composer Versioning - an article about Composer version
Composer Stability Flags - An article about Composer stability flags
Innocent Villagefolk or a Pillagin’ Pirate? - An article about PHP getting ideas from other languages
Predicting Random Numbers in PHP - an article about generating random numbers
A 20 Point List for Preventing XSS in PHP - An article about preventing XSS
PHP Sucks! But I Like It! - An article about the pros and cons of PHP
PHP Is Much Better Than You Think - An article about the PHP language and ecosystem

PHP Internals Reading PHP kernel reading

Read information related to PHP kernel or performance

PHP RFCs - PHP RFCs home page (request comments)
PHP Internals Book - An online book about the PHP kernel written by three core developers
Print vs Echo, Which One is Faster? - An article about printing and echo performance
The PHP Ternary Operator. Fast or Not? - An article about the performance of ternary operations
Disproving the Single Quotes Myth - An article about the performance of single and double quoted strings
You’re Being Lied To - An article about kernel ZVALs
How Long is a Piece of String - An article about the principle of strings
Understanding OpCodes - an article about pseudocode
How Foreach Works -StackOverflow Details about foreach answer
When Does Foreach Copy? - An article about the principle of foreach
How Big Are PHP Arrays (And Values) Really? - An article about the principle of arrays
Why Objects (Usually) Use Less Memory Than Arrays - An article about the principles of objects and arrays
PHP Evaluation Order - An article about PHP evaluation order
PHP source code for developers: 1 2 3 4 - Series about PHP source code
Garbage Collection: 1 2 3 Series on PHP Garbage Collection Principles