Welcome There’s a lot of outdated information on the Web that leads new PHP users astray, propagating bad practices and insecure code. PHP: The Right Way is an easy-to-read, quick reference for PHP popular coding standards, links to authoritative tutorials around the Web and what the contributors consider to be best practices at the present time. There is no canonical way to use PHP. This website aims to introduce new PHP developers to some topics which they may not discover until it is too late, and aims to give seasoned pros some fresh ideas on those topics they’ve been doing for years without ever reconsidering. This website will also not tell you which tools to use, but instead offer suggestions for multiple options, when possible explaining the differences in approach and use-case. This is a living document and will continue to be updated with more helpful information and examples as they become available. Translations PHP: The Right Way is translated into many different languages: English

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繁體中文 Book The most recent version of PHP: The Right Way is also available in PDF, EPUB and MOBI formats. Go to Leanpub How to Contribute Help make this website the best resource for new PHP programmers! Contribute on GitHub

Getting Started

Use the Current Stable Version (7.4) If you are getting started with PHP, start with the current stable release of PHP 7.4. PHP 7.x adds many new features over the older 5.x versions. The engine has been largely re-written, and PHP is now even quicker than older versions. You should try to upgrade to the latest stable version quickly - PHP 5.6 is already End of Life. Upgrading is easy, as there are not many backwards compatibility breaks. If you are not sure which version a function or feature is in, you can check the PHP documentation on the php.net website.

Built-in web server With PHP 5.4 or newer, you can start learning PHP without installing and configuring a full-fledged web server. To start the server, run the following command from your terminal in your project’s web root: > php -S localhost:8000 Learn about the built-in, command line web server

Mac Setup macOS comes prepackaged with PHP but it is normally a little behind the latest stable release. There are multiple ways to install the latest PHP version on macOS. Install PHP via Homebrew Homebrew is a package manager for macOS that helps you easily install PHP and various extensions. The Homebrew core repository provides “formulae” for PHP 5.6, 7.0, 7.1, 7.2, 7.3 and 7.4. Install the latest version with this command: brew install php@7.4 You can switch between Homebrew PHP versions by modifying your PATH variable. Alternatively, you can use brew-php-switcher to switch PHP versions automatically. Install PHP via Macports The MacPorts Project is an open-source community initiative to design an easy-to-use system for compiling, installing, and upgrading either command-line, X11 or Aqua based open-source software on the OS X operating system. MacPorts supports pre-compiled binaries, so you don’t need to recompile every dependency from the source tarball files, it saves your life if you don’t have any package installed on your system. At this point, you can install php54 , php55 , php56 , php70 , php71 , php72 , php73 or php74 using the port install command, for example: sudo port install php56 sudo port install php74 And you can run select command to switch your active PHP: sudo port select --set php php74 Install PHP via phpbrew phpbrew is a tool for installing and managing multiple PHP versions. This can be really useful if two different applications/projects require different versions of PHP, and you are not using virtual machines. Install PHP via Liip’s binary installer Another popular option is php-osx.liip.ch which provides one liner installation methods for versions 5.3 through 7.3. It doesn’t overwrite the PHP binaries installed by Apple, but installs everything in a separate location (/usr/local/php5). Compile from Source Another option that gives you control over the version of PHP you install, is to compile it yourself. In that case be sure to have installed either Xcode or Apple’s substitute “Command Line Tools for XCode” downloadable from Apple’s Mac Developer Center. All-in-One Installers The solutions listed above mainly handle PHP itself, and do not supply things like Apache, Nginx or a SQL server. “All-in-one” solutions such as MAMP and XAMPP will install these other bits of software for you and tie them all together, but ease of setup comes with a trade-off of flexibility.

Windows Setup You can download the binaries from windows.php.net/download. After the extraction of PHP, it is recommended to set the PATH to the root of your PHP folder (where php.exe is located) so you can execute PHP from anywhere. For learning and local development, you can use the built in webserver with PHP 5.4+ so you don’t need to worry about configuring it. If you would like an “all-in-one” which includes a full-blown webserver and MySQL too then tools such as the Web Platform Installer, XAMPP, EasyPHP, OpenServer and WAMP will help get a Windows development environment up and running fast. That said, these tools will be a little different from production so be careful of environment differences if you are working on Windows and deploying to Linux. If you need to run your production system on Windows, then IIS7 will give you the most stable and best performance. You can use phpmanager (a GUI plugin for IIS7) to make configuring and managing PHP simple. IIS7 comes with FastCGI built in and ready to go, you just need to configure PHP as a handler. For support and additional resources there is a dedicated area on iis.net for PHP. Generally running your application on different environment in development and production can lead to strange bugs popping up when you go live. If you are developing on Windows and deploying to Linux (or anything non-Windows) then you should consider using a Virtual Machine. Chris Tankersley has a very helpful blog post on what tools he uses to do PHP development using Windows.

Common Directory structure A common question among those starting out with writing programs for the web is, “where do I put my stuff?” Over the years, this answer has consistently been “where the DocumentRoot is.” Although this answer is not complete, it’s a great place to start. For security reasons, configuration files should not be accessible by a site’s visitors; therefore, public scripts are kept in a public directory and private configurations and data are kept outside of that directory. For each team, CMS, or framework one works in, a standard directory structure is used by each of those entities. However, if one is starting a project alone, knowing which filesystem structure to use can be daunting. Paul M. Jones has done some fantastic research into common practices of tens of thousands of github projects in the realm of PHP. He has compiled a standard file and directory structure, the Standard PHP Package Skeleton, based on this research. In this directory structure, DocumentRoot should point to public/ , unit tests should be in the tests/ directory, and third party libraries, as installed by composer, belong in the vendor/ directory. For other files and directories, abiding by the Standard PHP Package Skeleton will make the most sense to contributors of a project.

Language Highlights

Namespaces As mentioned above, the PHP community has a lot of developers creating lots of code. This means that one library’s PHP code might use the same class name as another. When both libraries are used in the same namespace, they collide and cause trouble. Namespaces solve this problem. As described in the PHP reference manual, namespaces may be compared to operating system directories that namespace files; two files with the same name may co-exist in separate directories. Likewise, two PHP classes with the same name may co-exist in separate PHP namespaces. It’s as simple as that. It is important for you to namespace your code so that it may be used by other developers without fear of colliding with other libraries. One recommended way to use namespaces is outlined in PSR-4, which aims to provide a standard file, class and namespace convention to allow plug-and-play code. In October 2014 the PHP-FIG deprecated the previous autoloading standard: PSR-0. Both PSR-0 and PSR-4 are still perfectly usable. The latter requires PHP 5.3, so many PHP 5.2-only projects implement PSR-0. If you’re going to use an autoloader standard for a new application or package, look into PSR-4. Read about Namespaces

Read about PSR-0

Read about PSR-4

Standard PHP Library The Standard PHP Library (SPL) is packaged with PHP and provides a collection of classes and interfaces. It is made up primarily of commonly needed datastructure classes (stack, queue, heap, and so on), and iterators which can traverse over these datastructures or your own classes which implement SPL interfaces. Read about the SPL

SPL video course on Lynda.com(Paid)

Command Line Interface PHP was created to write web applications, but is also useful for scripting command line interface (CLI) programs. Command line PHP programs can help automate common tasks like testing, deployment, and application administration. CLI PHP programs are powerful because you can use your app’s code directly without having to create and secure a web GUI for it. Just be sure not to put your CLI PHP scripts in your public web root! Try running PHP from your command line: > php -i The -i option will print your PHP configuration just like the phpinfo() function. The -a option provides an interactive shell, similar to ruby’s IRB or python’s interactive shell. There are a number of other useful command line options, too. Let’s write a simple “Hello, $name” CLI program. To try it out, create a file named hello.php , as below. <?php if ( $argc !== 2 ) { echo "Usage: php hello.php <name>.

" ; exit ( 1 ); } $name = $argv [ 1 ]; echo "Hello, $name

" ; PHP sets up two special variables based on the arguments your script is run with. $argc is an integer variable containing the argument count and $argv is an array variable containing each argument’s value. The first argument is always the name of your PHP script file, in this case hello.php . The exit() expression is used with a non-zero number to let the shell know that the command failed. Commonly used exit codes can be found here. To run our script, above, from the command line: > php hello.php Usage: php hello.php <name> > php hello.php world Hello, world Learn about running PHP from the command line

Xdebug One of the most useful tools in software development is a proper debugger. It allows you to trace the execution of your code and monitor the contents of the stack. Xdebug, PHP’s debugger, can be utilized by various IDEs to provide Breakpoints and stack inspection. It can also allow tools like PHPUnit and KCacheGrind to perform code coverage analysis and code profiling. If you find yourself in a bind, willing to resort to var_dump() / print_r() , and you still can’t find the solution - maybe you need to use the debugger. Installing Xdebug can be tricky, but one of its most important features is “Remote Debugging” - if you develop code locally and then test it inside a VM or on another server, Remote Debugging is the feature that you will want to enable right away. Traditionally, you will modify your Apache VHost or .htaccess file with these values: php_value xdebug.remote_host 192.168.?.? php_value xdebug.remote_port 9000 The “remote host” and “remote port” will correspond to your local computer and the port that you configure your IDE to listen on. Then it’s just a matter of putting your IDE into “listen for connections” mode, and loading the URL: http://your-website.example.com/index.php?XDEBUG_SESSION_START=1 Your IDE will now intercept the current state as the script executes, allowing you to set breakpoints and probe the values in memory. Graphical debuggers make it very easy to step through code, inspect variables, and eval code against the live runtime. Many IDE’s have built-in or plugin-based support for graphical debugging with Xdebug. MacGDBp is a free, open-source, stand-alone Xdebug GUI for Mac. Learn more about Xdebug

Learn more about MacGDBp

Dependency Management There are a ton of PHP libraries, frameworks, and components to choose from. Your project will likely use several of them — these are project dependencies. Until recently, PHP did not have a good way to manage these project dependencies. Even if you managed them manually, you still had to worry about autoloaders. That is no longer an issue. Currently there are two major package management systems for PHP - Composer and PEAR. Composer is currently the most popular package manager for PHP, however for a long time PEAR was the primary package manager in use. Knowing PEAR’s history is a good idea, since you may still find references to it even if you never use it.

Composer and Packagist Composer is the recommended dependency manager for PHP. List your project’s dependencies in a composer.json file and, with a few simple commands, Composer will automatically download your project’s dependencies and setup autoloading for you. Composer is analogous to NPM in the node.js world, or Bundler in the Ruby world. There is a plethora of PHP libraries that are compatible with Composer and ready to be used in your project. These “packages” are listed on Packagist, the official repository for Composer-compatible PHP libraries. How to Install Composer The safest way to download composer is by following the official instructions. This will verify the installer is not corrupt or tampered with. The installer installs a composer.phar binary in your current working directory. We recommend installing Composer globally (e.g. a single copy in /usr/local/bin ). To do so, run this command next: mv composer.phar /usr/local/bin/composer Note: If the above fails due to permissions, prefix with sudo . To run a locally installed Composer you’d use php composer.phar , globally it’s simply composer . Installing on Windows For Windows users the easiest way to get up and running is to use the ComposerSetup installer, which performs a global install and sets up your $PATH so that you can just call composer from any directory in your command line. How to Define and Install Dependencies Composer keeps track of your project’s dependencies in a file called composer.json . You can manage it by hand if you like, or use Composer itself. The composer require command adds a project dependency and if you don’t have a composer.json file, one will be created. Here’s an example that adds Twig as a dependency of your project. composer require twig/twig:^2.0 Alternatively, the composer init command will guide you through creating a full composer.json file for your project. Either way, once you’ve created your composer.json file you can tell Composer to download and install your dependencies into the vendor/ directory. This also applies to projects you’ve downloaded that already provide a composer.json file: composer install Next, add this line to your application’s primary PHP file; this will tell PHP to use Composer’s autoloader for your project dependencies. <?php require 'vendor/autoload.php' ; Now you can use your project dependencies, and they’ll be autoloaded on demand. Updating your dependencies Composer creates a file called composer.lock which stores the exact version of each package it downloaded when you first ran composer install . If you share your project with others, ensure the composer.lock file is included, so that when they run composer install they’ll get the same versions as you. To update your dependencies, run composer update . Don’t use composer update when deploying, only composer install , otherwise you may end up with different package versions on production. This is most useful when you define your version requirements flexibly. For instance, a version requirement of ~1.8 means “anything newer than 1.8.0 , but less than 2.0.x-dev ”. You can also use the * wildcard as in 1.8.* . Now Composer’s composer update command will upgrade all your dependencies to the newest version that fits the restrictions you define. To receive notifications about new version releases you can sign up for libraries.io, a web service that can monitor dependencies and send you alerts on updates. Checking your dependencies for security issues The Security Advisories Checker is a web service and a command-line tool, both will examine your composer.lock file and tell you if you need to update any of your dependencies. Handling global dependencies with Composer Composer can also handle global dependencies and their binaries. Usage is straight-forward, all you need to do is prefix your command with global . If for example you wanted to install PHPUnit and have it available globally, you’d run the following command: composer global require phpunit/phpunit This will create a ~/.composer folder where your global dependencies reside. To have the installed packages’ binaries available everywhere, you’d then add the ~/.composer/vendor/bin folder to your $PATH variable. Learn about Composer

PEAR A veteran package manager that some PHP developers enjoy is PEAR. It behaves similarly to Composer, but has some notable differences. PEAR requires each package to have a specific structure, which means that the author of the package must prepare it for usage with PEAR. Using a project which was not prepared to work with PEAR is not possible. PEAR installs packages globally, which means after installing them once they are available to all projects on that server. This can be good if many projects rely on the same package with the same version but might lead to problems if version conflicts between two projects arise. How to install PEAR You can install PEAR by downloading the .phar installer and executing it. The PEAR documentation has detailed install instructions for every operating system. If you are using Linux, you can also have a look at your distribution package manager. Debian and Ubuntu, for example, have an apt php-pear package. How to install a package If the package is listed on the PEAR packages list, you can install it by specifying the official name: pear install foo If the package is hosted on another channel, you need to discover the channel first and also specify it when installing. See the Using channel docs for more information on this topic. Learn about PEAR Handling PEAR dependencies with Composer If you are already using Composer and you would like to install some PEAR code too, you can use Composer to handle your PEAR dependencies. This example will install code from pear2.php.net : { "repositories" : [ { "type" : "pear" , "url" : "https://pear2.php.net" } ], "require" : { "pear-pear2/PEAR2_Text_Markdown" : "*" , "pear-pear2/PEAR2_HTTP_Request" : "*" } } The first section "repositories" will be used to let Composer know it should “initialize” (or “discover” in PEAR terminology) the pear repo. Then the require section will prefix the package name like this: pear-channel/Package The “pear” prefix is hardcoded to avoid any conflicts, as a pear channel could be the same as another packages vendor name for example, then the channel short name (or full URL) can be used to reference which channel the package is in. When this code is installed it will be available in your vendor directory and automatically available through the Composer autoloader: vendor/pear-pear2.php.net/PEAR2_HTTP_Request/pear2/HTTP/Request.php To use this PEAR package simply reference it like so: <?php $request = new pear2\HTTP\Request (); Learn more about using PEAR with Composer

Coding Practices

The Basics PHP is a vast language that allows coders of all levels the ability to produce code not only quickly, but efficiently. However, while advancing through the language, we often forget the basics that we first learnt (or overlooked) in favor of short cuts and/or bad habits. To help combat this common issue, this section is aimed at reminding coders of the basic coding practices within PHP. Continue reading on The Basics

Design Patterns When you are building your application it is helpful to use common patterns in your code and common patterns for the overall structure of your project. Using common patterns is helpful because it makes it much easier to manage your code and lets other developers quickly understand how everything fits together. If you use a framework then most of the higher level code and project structure will be based on that framework, so a lot of the pattern decisions are made for you. But it is still up to you to pick out the best patterns to follow in the code you build on top of the framework. If, on the other hand, you are not using a framework to build your application then you have to find the patterns that best suit the type and size of application that you’re building. You can learn more about PHP design patterns and see working examples at: https://designpatternsphp.readthedocs.io/

Internationalization (i18n) and Localization (l10n) Disclaimer for newcomers: i18n and l10n are numeronyms, a kind of abbreviation where numbers are used to shorten words - in our case, internationalization becomes i18n and localization, l10n. First of all, we need to define those two similar concepts and other related things: Internationalization is when you organize your code so it can be adapted to different languages or regions without refactorings. This action is usually done once - preferably, at the beginning of the project, or else you will probably need some huge changes in the source!

is when you organize your code so it can be adapted to different languages or regions without refactorings. This action is usually done once - preferably, at the beginning of the project, or else you will probably need some huge changes in the source! Localization happens when you adapt the interface (mainly) by translating contents, based on the i18n work done before. It usually is done every time a new language or region needs support and is updated when new interface pieces are added, as they need to be available in all supported languages.

happens when you adapt the interface (mainly) by translating contents, based on the i18n work done before. It usually is done every time a new language or region needs support and is updated when new interface pieces are added, as they need to be available in all supported languages. Pluralization defines the rules required between distinct languages to interoperate strings containing numbers and counters. For instance, in English when you have only one item, it is singular, and anything different from that is called plural; plural in this language is indicated by adding an S after some words, and sometimes changes parts of it. In other languages, such as Russian or Serbian, there are two plural forms in addition to the singular - you may even find languages with a total of four, five or six forms, such as Slovenian, Irish or Arabic. Common ways to implement The easiest way to internationalize PHP software is by using array files and using those strings in templates, such as <h1><?=$TRANS['title_about_page']?></h1> . This way is, however, hardly recommended for serious projects, as it poses some maintenance issues along the road - some might appear in the very beginning, such as pluralization. So, please, don’t try this if your project will contain more than a couple of pages. The most classic way and often taken as reference for i18n and l10n is a Unix tool called gettext . It dates back to 1995 and is still a complete implementation for translating software. It is easy enough to get running, while still sporting powerful supporting tools. It is about Gettext we will be talking here. Also, to help you not get messy over the command-line, we will be presenting a great GUI application that can be used to easily update your l10n source There are common libraries used that support Gettext and other implementations of i18n. Some of them may seem easier to install or sport additional features or i18n file formats. In this document, we focus on the tools provided with the PHP core, but here we list others for completion: aura/intl: Provides internationalization (I18N) tools, specifically package-oriented per-locale message translation. It uses array formats for message. Does not provide a message extractor, but does provide advanced message formatting via the intl extension (including pluralized messages).

extension (including pluralized messages). oscarotero/Gettext: Gettext support with an OO interface; includes improved helper functions, powerful extractors for several file formats (some of them not supported natively by the gettext command), and can also export to other formats besides .mo/.po files. Can be useful if you need to integrate your translation files into other parts of the system, like a JavaScript interface.

command), and can also export to other formats besides files. Can be useful if you need to integrate your translation files into other parts of the system, like a JavaScript interface. symfony/translation: supports a lot of different formats, but recommends using verbose XLIFF’s. Doesn’t include helper functions nor a built-in extractor, but supports placeholders using strtr() internally.

internally. zend/i18n: supports array and INI files, or Gettext formats. Implements a caching layer to save you from reading the filesystem every time. It also includes view helpers, and locale-aware input filters and validators. However, it has no message extractor. Other frameworks also include i18n modules, but those are not available outside of their codebases: Laravel supports basic array files, has no automatic extractor but includes a @lang helper for template files.

helper for template files. Yii supports array, Gettext, and database-based translation, and includes a messages extractor. It is backed by the Intl extension, available since PHP 5.3, and based on the ICU project; this enables Yii to run powerful replacements, like spelling out numbers, formatting dates, times, intervals, currency, and ordinals. If you decide to go for one of the libraries that provide no extractors, you may want to use the gettext formats, so you can use the original gettext toolchain (including Poedit) as described in the rest of the chapter. Gettext Installation You might need to install Gettext and the related PHP library by using your package manager, like apt-get or yum . After installed, enable it by adding extension=gettext.so (Linux/Unix) or extension=php_gettext.dll (Windows) to your php.ini . Here we will also be using Poedit to create translation files. You will probably find it in your system’s package manager; it is available for Unix, Mac, and Windows, and can be downloaded for free on their website as well. Structure Types of files There are three files you usually deal with while working with gettext. The main ones are PO (Portable Object) and MO (Machine Object) files, the first being a list of readable “translated objects” and the second, the corresponding binary to be interpreted by gettext when doing localization. There’s also a POT (Template) file, which simply contains all existing keys from your source files, and can be used as a guide to generate and update all PO files. Those template files are not mandatory: depending on the tool you are using to do l10n, you can go just fine with only PO/MO files. You will always have one pair of PO/MO files per language and region, but only one POT per domain. Domains There are some cases, in big projects, where you might need to separate translations when the same words convey different meaning given a context. In those cases, you split them into different domains. They are, basically, named groups of POT/PO/MO files, where the filename is the said translation domain. Small and medium-sized projects usually, for simplicity, use only one domain; its name is arbitrary, but we will be using “main” for our code samples. In Symfony projects, for example, domains are used to separate the translation for validation messages. Locale code A locale is simply a code that identifies one version of a language. It is defined following the ISO 639-1 and ISO 3166-1 alpha-2 specs: two lower-case letters for the language, optionally followed by an underline and two upper-case letters identifying the country or regional code. For rare languages, three letters are used. For some speakers, the country part may seem redundant. In fact, some languages have dialects in different countries, such as Austrian German ( de_AT ) or Brazilian Portuguese ( pt_BR ). The second part is used to distinguish between those dialects - when it is not present, it is taken as a “generic” or “hybrid” version of the language. Directory structure To use Gettext, we will need to adhere to a specific structure of folders. First, you will need to select an arbitrary root for your l10n files in your source repository. Inside it, you will have a folder for each needed locale, and a fixed LC_MESSAGES folder that will contain all your PO/MO pairs. Example: <project root> ├─ src/ ├─ templates/ └─ locales/ ├─ forum.pot ├─ site.pot ├─ de/ │ └─ LC_MESSAGES/ │ ├─ forum.mo │ ├─ forum.po │ ├─ site.mo │ └─ site.po ├─ es_ES/ │ └─ LC_MESSAGES/ │ └─ ... ├─ fr/ │ └─ ... ├─ pt_BR/ │ └─ ... └─ pt_PT/ └─ ... Plural forms As we said in the introduction, different languages might sport different plural rules. However, gettext saves us from this trouble once again. When creating a new .po file, you will have to declare the plural rules for that language, and translated pieces that are plural-sensitive will have a different form for each of those rules. When calling Gettext in code, you will have to specify the number related to the sentence, and it will work out the correct form to use - even using string substitution if needed. Plural rules include the number of plurals available and a boolean test with n that would define in which rule the given number falls (starting the count with 0). For example: Japanese: nplurals=1; plural=0 - only one rule

- only one rule English: nplurals=2; plural=(n != 1); - two rules, first if N is one, second rule otherwise

- two rules, first if N is one, second rule otherwise Brazilian Portuguese: nplurals=2; plural=(n > 1); - two rules, second if N is bigger than one, first otherwise Now that you understood the basis of how plural rules works - and if you didn’t, please look at a deeper explanation on the LingoHub tutorial -, you might want to copy the ones you need from a list instead of writing them by hand. When calling out Gettext to do localization on sentences with counters, you will have to provide it the related number as well. Gettext will work out what rule should be in effect and use the correct localized version. You will need to include in the .po file a different sentence for each plural rule defined. Sample implementation After all that theory, let’s get a little practical. Here’s an excerpt of a .po file - don’t mind with its format, but with the overall content instead; you will learn how to edit it easily later: msgid "" msgstr "" "Language: pt_BR

" "Content-Type: text/plain; charset=UTF-8

" "Plural-Forms: nplurals=2; plural=(n > 1);

" msgid "We are now translating some strings" msgstr "Nós estamos traduzindo algumas strings agora" msgid "Hello %1$s! Your last visit was on %2$s" msgstr "Olá %1$s! Sua última visita foi em %2$s" msgid "Only one unread message" msgid_plural "%d unread messages" msgstr[0] "Só uma mensagem não lida" msgstr[1] "%d mensagens não lidas" The first section works like a header, having the msgid and msgstr especially empty. It describes the file encoding, plural forms and other things that are less relevant. The second section translates a simple string from English to Brazilian Portuguese, and the third does the same, but leveraging string replacement from sprintf so the translation may contain the user name and visit date. The last section is a sample of pluralization forms, displaying the singular and plural version as msgid in English and their corresponding translations as msgstr 0 and 1 (following the number given by the plural rule). There, string replacement is used as well so the number can be seen directly in the sentence, by using %d . The plural forms always have two msgid (singular and plural), so it is advised not to use a complex language as the source of translation. Discussion on l10n keys As you might have noticed, we are using as source ID the actual sentence in English. That msgid is the same used throughout all your .po files, meaning other languages will have the same format and the same msgid fields but translated msgstr lines. Talking about translation keys, there are two main “schools” here: msgid as a real sentence. The main advantages are: if there are pieces of the software untranslated in any given language, the key displayed will still maintain some meaning. Example: if you happen to translate by heart from English to Spanish but need help to translate to French, you might publish the new page with missing French sentences, and parts of the website would be displayed in English instead;

it is much easier for the translator to understand what’s going on and do a proper translation based on the msgid ;

; it gives you “free” l10n for one language - the source one;

The only disadvantage: if you need to change the actual text, you would need to replace the same msgid across several language files. msgid as a unique, structured key. It would describe the sentence role in the application in a structured way, including the template or part where the string is located instead of its content. it is a great way to have the code organized, separating the text content from the template logic.

however, that could bring problems to the translator that would miss the context. A source language file would be needed as a basis for other translations. Example: the developer would ideally have an en.po file, that translators would read to understand what to write in fr.po for instance.

file, that translators would read to understand what to write in for instance. missing translations would display meaningless keys on screen ( top_menu.welcome instead of Hello there, User! on the said untranslated French page). That is good it as would force translation to be complete before publishing - however, bad as translation issues would be remarkably awful in the interface. Some libraries, though, include an option to specify a given language as “fallback”, having a similar behavior as the other approach. The Gettext manual favors the first approach as, in general, it is easier for translators and users in case of trouble. That is how we will be working here as well. However, the Symfony documentation favors keyword-based translation, to allow for independent changes of all translations without affecting templates as well. Everyday usage In a typical application, you would use some Gettext functions while writing static text in your pages. Those sentences would then appear in .po files, get translated, compiled into .mo files and then, used by Gettext when rendering the actual interface. Given that, let’s tie together what we have discussed so far in a step-by-step example: 1. A sample template file, including some different gettext calls <?php include 'i18n_setup.php' ?> <div id= "header" > <h1> <?= sprintf ( gettext ( 'Welcome, %s!' ), $name ) ?> </h1> <!-- code indented this way only for legibility --> <?php if ( $unread ) : ?> <h2> <?= sprintf ( ngettext ( 'Only one unread message' , '%d unread messages' , $unread ), $unread ) ?> </h2> <?php endif ?> </div> <h1> <?= gettext ( 'Introduction' ) ?> </h1> <p> <?= gettext ( 'We\'re now translating some strings' ) ?> </p> gettext() simply translates a msgid into its corresponding msgstr for a given language. There’s also the shorthand function _() that works the same way;

simply translates a into its corresponding for a given language. There’s also the shorthand function that works the same way; ngettext() does the same but with plural rules;

does the same but with plural rules; there’s also dgettext() and dngettext() , that allows you to override the domain for a single call. More on domain configuration in the next example. 2. A sample setup file ( i18n_setup.php as used above), selecting the correct locale and configuring Gettext <?php /** * Verifies if the given $locale is supported in the project * @param string $locale * @return bool */ function valid ( $locale ) { return in_array ( $locale , [ 'en_US' , 'en' , 'pt_BR' , 'pt' , 'es_ES' , 'es' ]); } //setting the source/default locale, for informational purposes $lang = 'en_US' ; if ( isset ( $_GET [ 'lang' ]) && valid ( $_GET [ 'lang' ])) { // the locale can be changed through the query-string $lang = $_GET [ 'lang' ]; //you should sanitize this! setcookie ( 'lang' , $lang ); //it's stored in a cookie so it can be reused } elseif ( isset ( $_COOKIE [ 'lang' ]) && valid ( $_COOKIE [ 'lang' ])) { // if the cookie is present instead, let's just keep it $lang = $_COOKIE [ 'lang' ]; //you should sanitize this! } elseif ( isset ( $_SERVER [ 'HTTP_ACCEPT_LANGUAGE' ])) { // default: look for the languages the browser says the user accepts $langs = explode ( ',' , $_SERVER [ 'HTTP_ACCEPT_LANGUAGE' ]); array_walk ( $langs , function ( & $lang ) { $lang = strtr ( strtok ( $lang , ';' ), [ '-' => '_' ]); }); foreach ( $langs as $browser_lang ) { if ( valid ( $browser_lang )) { $lang = $browser_lang ; break ; } } } // here we define the global system locale given the found language putenv ( "LANG= $lang " ); // this might be useful for date functions (LC_TIME) or money formatting (LC_MONETARY), for instance setlocale ( LC_ALL , $lang ); // this will make Gettext look for ../locales/<lang>/LC_MESSAGES/main.mo bindtextdomain ( 'main' , '../locales' ); // indicates in what encoding the file should be read bind_textdomain_codeset ( 'main' , 'UTF-8' ); // if your application has additional domains, as cited before, you should bind them here as well bindtextdomain ( 'forum' , '../locales' ); bind_textdomain_codeset ( 'forum' , 'UTF-8' ); // here we indicate the default domain the gettext() calls will respond to textdomain ( 'main' ); // this would look for the string in forum.mo instead of main.mo // echo dgettext('forum', 'Welcome back!'); ?> 3. Preparing translation for the first run One of the great advantages Gettext has over custom framework i18n packages is its extensive and powerful file format. “Oh man, that’s quite hard to understand and edit by hand, a simple array would be easier!” Make no mistake, applications like Poedit are here to help - a lot. You can get the program from their website, it’s free and available for all platforms. It’s a pretty easy tool to get used to, and a very powerful one at the same time - using all features Gettext has available. This guide is based on PoEdit 1.8. In the first run, you should select “File > New…” from the menu. You’ll be asked straight ahead for the language: here you can select/filter the language you want to translate to, or use that format we mentioned before, such as en_US or pt_BR . Now, save the file - using that directory structure we mentioned as well. Then you should click “Extract from sources”, and here you’ll configure various settings for the extraction and translation tasks. You’ll be able to find all those later through “Catalog > Properties”: Source paths: here you must include all folders from the project where gettext() (and siblings) are called - this is usually your templates/views folder(s). This is the only mandatory setting;

(and siblings) are called - this is usually your templates/views folder(s). This is the only mandatory setting; Translation properties: Project name and version, Team and Team’s email address: useful information that goes in the .po file header; Plural forms: here go those rules we mentioned before - there’s a link in there with samples as well. You can leave it with the default option most of the time, as PoEdit already includes a handy database of plural rules for many languages. Charsets: UTF-8, preferably; Source code charset: set here the charset used by your codebase - probably UTF-8 as well, right?

Source keywords: The underlying software knows how gettext() and similar function calls look like in several programming languages, but you might as well create your own translation functions. It will be here you’ll add those other methods. This will be discussed later in the “Tips” section. After setting those points it will run a scan through your source files to find all the localization calls. After every scan PoEdit will display a summary of what was found and what was removed from the source files. New entries will fed empty into the translation table, and you’ll start typing in the localized versions of those strings. Save it and a .mo file will be (re)compiled into the same folder and ta-dah: your project is internationalized. 4. Translating strings As you may have noticed before, there are two main types of localized strings: simple ones and those with plural forms. The first ones have simply two boxes: source and localized string. The source string cannot be modified as Gettext/Poedit do not include the powers to alter your source files - you should change the source itself and rescan the files. Tip: you may right-click a translation line and it will hint you with the source files and lines where that string is being used. On the other hand, plural form strings include two boxes to show the two source strings, and tabs so you can configure the different final forms. Whenever you change your sources and need to update the translations, just hit Refresh and Poedit will rescan the code, removing non-existent entries, merging the ones that changed and adding new ones. It may also try to guess some translations, based on other ones you did. Those guesses and the changed entries will receive a “Fuzzy” marker, indicating it needs review, appearing golden in the list. It is also useful if you have a translation team and someone tries to write something they are not sure about: just mark Fuzzy, and someone else will review later. Finally, it is advised to leave “View > Untranslated entries first” marked, as it will help you a lot to not forget any entry. From that menu, you can also open parts of the UI that allow you to leave contextual information for translators if needed. Tips & Tricks Possible caching issues If you are running PHP as a module on Apache ( mod_php ), you might face issues with the .mo file being cached. It happens the first time it is read, and then, to update it, you might need to restart the server. On Nginx and PHP5 it usually takes only a couple of page refreshes to refresh the translation cache, and on PHP7 it is rarely needed. Additional helper functions As preferred by many people, it is easier to use _() instead of gettext() . Many custom i18n libraries from frameworks use something similar to t() as well, to make translated code shorter. However, that is the only function that sports a shortcut. You might want to add in your project some others, such as __() or _n() for ngettext() , or maybe a fancy _r() that would join gettext() and sprintf() calls. Other libraries, such as oscarotero’s Gettext also provide helper functions like these. In those cases, you’ll need to instruct the Gettext utility on how to extract the strings from those new functions. Don’t be afraid; it is very easy. It is just a field in the .po file, or a Settings screen on Poedit. In the editor, that option is inside “Catalog > Properties > Source keywords”. Remember: Gettext already knows the default functions for many languages, so don’t be afraid if that list seems empty. You need to include there the specifications of those new functions, following a specific format: if you create something like t() that simply returns the translation for a string, you can specify it as t . Gettext will know the only function argument is the string to be translated;

that simply returns the translation for a string, you can specify it as . Gettext will know the only function argument is the string to be translated; if the function has more than one argument, you can specify in which one the first string is - and if needed, the plural form as well. For instance, if we call our function like this: __('one user', '%d users', $number) , the specification would be __:1,2 , meaning the first form is the first argument, and the second form is the second argument. If your number comes as the first argument instead, the spec would be __:2,3 , indicating the first form is the second argument, and so on. After including those new rules in the .po file, a new scan will bring in your new strings just as easy as before. References Wikipedia: i18n and l10n

Wikipedia: Gettext

LingoHub: PHP internationalization with gettext tutorial

PHP Manual: Gettext

Gettext Manual

Dependency Injection From Wikipedia: Dependency injection is a software design pattern that allows the removal of hard-coded dependencies and makes it possible to change them, whether at run-time or compile-time. This quote makes the concept sound much more complicated than it actually is. Dependency Injection is providing a component with its dependencies either through constructor injection, method calls or the setting of properties. It is that simple.

Basic Concept We can demonstrate the concept with a simple, yet naive example. Here we have a Database class that requires an adapter to speak to the database. We instantiate the adapter in the constructor and create a hard dependency. This makes testing difficult and means the Database class is very tightly coupled to the adapter. <?php namespace Database ; class Database { protected $adapter ; public function __construct () { $this -> adapter = new MySqlAdapter ; } } class MysqlAdapter {} This code can be refactored to use Dependency Injection and therefore loosen the dependency. <?php namespace Database ; class Database { protected $adapter ; public function __construct ( MySqlAdapter $adapter ) { $this -> adapter = $adapter ; } } class MysqlAdapter {} Now we are giving the Database class its dependency rather than creating it itself. We could even create a method that would accept an argument of the dependency and set it that way, or if the $adapter property was public we could set it directly.

Complex Problem If you have ever read about Dependency Injection then you have probably seen the terms “Inversion of Control” or “Dependency Inversion Principle”. These are the complex problems that Dependency Injection solves. Inversion of Control Inversion of Control is as it says, “inverting the control” of a system by keeping organizational control entirely separate from our objects. In terms of Dependency Injection, this means loosening our dependencies by controlling and instantiating them elsewhere in the system. For years, PHP frameworks have been achieving Inversion of Control, however, the question became, which part of control are we inverting, and where to? For example, MVC frameworks would generally provide a super object or base controller that other controllers must extend to gain access to its dependencies. This is Inversion of Control, however, instead of loosening dependencies, this method simply moved them. Dependency Injection allows us to more elegantly solve this problem by only injecting the dependencies we need, when we need them, without the need for any hard coded dependencies at all. S.O.L.I.D. Single Responsibility Principle The Single Responsibility Principle is about actors and high-level architecture. It states that “A class should have only one reason to change.” This means that every class should only have responsibility over a single part of the functionality provided by the software. The largest benefit of this approach is that it enables improved code reusability. By designing our class to do just one thing, we can use (or re-use) it in any other program without changing it. Open/Closed Principle The Open/Closed Principle is about class design and feature extensions. It states that “Software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification.” This means that we should design our modules, classes and functions in a way that when a new functionality is needed, we should not modify our existing code but rather write new code that will be used by existing code. Practically speaking, this means that we should write classes that implement and adhere to interfaces, then type-hint against those interfaces instead of specific classes. The largest benefit of this approach is that we can very easily extend our code with support for something new without having to modify existing code, meaning that we can reduce QA time, and the risk for negative impact to the application is substantially reduced. We can deploy new code, faster, and with more confidence. Liskov Substitution Principle The Liskov Substitution Principle is about subtyping and inheritance. It states that “Child classes should never break the parent class’ type definitions.” Or, in Robert C. Martin’s words, “Subtypes must be substitutable for their base types.” For example, if we have a FileInterface interface which defines an embed() method, and we have Audio and Video classes which both implement the FileInterface interface, then we can expect that the usage of the embed() method will always do the thing that we intend. If we later create a PDF class or a Gist class which implement the FileInterface interface, we will already know and understand what the embed() method will do. The largest benefit of this approach is that we have the ability to build flexible and easily-configurable programs, because when we change one object of a type (e.g., FileInterface ) to another we don’t need to change anything else in our program. Interface Segregation Principle The Interface Segregation Principle (ISP) is about business-logic-to-clients communication. It states that “No client should be forced to depend on methods it does not use.” This means that instead of having a single monolithic interface that all conforming classes need to implement, we should instead provide a set of smaller, concept-specific interfaces that a conforming class implements one or more of. For example, a Car or Bus class would be interested in a steeringWheel() method, but a Motorcycle or Tricycle class would not. Conversely, a Motorcycle or Tricycle class would be interested in a handlebars() method, but a Car or Bus class would not. There is no need to have all of these types of vehicles implement support for both steeringWheel() as well as handlebars() , so we should break-apart the source interface. Dependency Inversion Principle The Dependency Inversion Principle is about removing hard-links between discrete classes so that new functionality can be leveraged by passing a different class. It states that one should “Depend on Abstractions. Do not depend on concretions.”. Put simply, this means our dependencies should be interfaces/contracts or abstract classes rather than concrete implementations. We can easily refactor the above example to follow this principle. <?php namespace Database ; class Database { protected $adapter ; public function __construct ( AdapterInterface $adapter ) { $this -> adapter = $adapter ; } } interface AdapterInterface {} class MysqlAdapter implements AdapterInterface {} There are several benefits to the Database class now depending on an interface rather than a concretion. Consider that we are working in a team and the adapter is being worked on by a colleague. In our first example, we would have to wait for said colleague to finish the adapter before we could properly mock it for our unit tests. Now that the dependency is an interface/contract we can happily mock that interface knowing that our colleague will build the adapter based on that contract. An even bigger benefit to this method is that our code is now much more scalable. If a year down the line we decide that we want to migrate to a different type of database, we can write an adapter that implements the original interface and injects that instead, no more refactoring would be required as we can ensure that the adapter follows the contract set by the interface.

Containers The first thing you should understand about Dependency Injection Containers is that they are not the same thing as Dependency Injection. A container is a convenience utility that helps us implement Dependency Injection, however, they can be and often are misused to implement an anti-pattern, Service Location. Injecting a DI container as a Service Locator in to your classes arguably creates a harder dependency on the container than the dependency you are replacing. It also makes your code much less transparent and ultimately harder to test. Most modern frameworks have their own Dependency Injection Container that allows you to wire your dependencies together through configuration. What this means in practice is that you can write application code that is as clean and de- coupled as the framework it is built on.

Databases Many times your PHP code will use a database to persist information. You have a few options to connect and interact with your database. The recommended option until PHP 5.1.0 was to use native drivers such as mysqli, pgsql, mssql, etc. Native drivers are great if you are only using one database in your application, but if, for example, you are using MySQL and a little bit of MSSQL, or you need to connect to an Oracle database, then you will not be able to use the same drivers. You’ll need to learn a brand new API for each database — and that can get silly.

PDO Extension PDO is a database connection abstraction library — built into PHP since 5.1.0 — that provides a common interface to talk with many different databases. For example, you can use basically identical code to interface with MySQL or SQLite: <?php // PDO + MySQL $pdo = new PDO ( 'mysql:host=example.com;dbname=database' , 'user' , 'password' ); $statement = $pdo -> query ( "SELECT some_field FROM some_table" ); $row = $statement -> fetch ( PDO :: FETCH_ASSOC ); echo htmlentities ( $row [ 'some_field' ]); // PDO + SQLite $pdo = new PDO ( 'sqlite:/path/db/foo.sqlite' ); $statement = $pdo -> query ( "SELECT some_field FROM some_table" ); $row = $statement -> fetch ( PDO :: FETCH_ASSOC ); echo htmlentities ( $row [ 'some_field' ]); PDO will not translate your SQL queries or emulate missing features; it is purely for connecting to multiple types of database with the same API. More importantly, PDO allows you to safely inject foreign input (e.g. IDs) into your SQL queries without worrying about database SQL injection attacks. This is possible using PDO statements and bound parameters. Let’s assume a PHP script receives a numeric ID as a query parameter. This ID should be used to fetch a user record from a database. This is the wrong way to do this: <?php $pdo = new PDO ( 'sqlite:/path/db/users.db' ); $pdo -> query ( "SELECT name FROM users WHERE id = " . $_GET [ 'id' ]); // <-- NO! This is terrible code. You are inserting a raw query parameter into a SQL query. This will get you hacked in a heartbeat, using a practice called SQL Injection. Just imagine if a hacker passes in an inventive id parameter by calling a URL like http://domain.com/?id=1%3BDELETE+FROM+users . This will set the $_GET['id'] variable to 1;DELETE FROM users which will delete all of your users! Instead, you should sanitize the ID input using PDO bound parameters. <?php $pdo = new PDO ( 'sqlite:/path/db/users.db' ); $stmt = $pdo -> prepare ( 'SELECT name FROM users WHERE id = :id' ); $id = filter_input ( INPUT_GET , 'id' , FILTER_SANITIZE_NUMBER_INT ); // <-- filter your data first (see [Data Filtering](#data_filtering)), especially important for INSERT, UPDATE, etc. $stmt -> bindParam ( ':id' , $id , PDO :: PARAM_INT ); // <-- Automatically sanitized for SQL by PDO $stmt -> execute (); This is correct code. It uses a bound parameter on a PDO statement. This escapes the foreign input ID before it is introduced to the database preventing potential SQL injection attacks. For writes, such as INSERT or UPDATE, it’s especially critical to still filter your data first and sanitize it for other things (removal of HTML tags, JavaScript, etc). PDO will only sanitize it for SQL, not for your application. Learn about PDO You should also be aware that database connections use up resources and it was not unheard-of to have resources exhausted if connections were not implicitly closed, however this was more common in other languages. Using PDO you can implicitly close the connection by destroying the object by ensuring all remaining references to it are deleted, i.e. set to NULL. If you don’t do this explicitly, PHP will automatically close the connection when your script ends - unless of course you are using persistent connections. Learn about PDO connections

Interacting with Databases When developers first start to learn PHP, they often end up mixing their database interaction up with their presentation logic, using code that might look like this: <ul> <?php foreach ( $db -> query ( 'SELECT * FROM table' ) as $row ) { echo "<li>" . $row [ 'field1' ] . " - " . $row [ 'field1' ] . "</li>" ; } ?> </ul> This is bad practice for all sorts of reasons, mainly that it’s hard to debug, hard to test, hard to read and it is going to output a lot of fields if you don’t put a limit on there. While there are many other solutions to doing this - depending on if you prefer OOP or functional programming - there must be some element of separation. Consider the most basic step: <?php function getAllFoos ( $db ) { return $db -> query ( 'SELECT * FROM table' ); } $results = getAllFoos ( $db ); foreach ( $results as $row ) { echo "<li>" . $row [ 'field1' ] . " - " . $row [ 'field1' ] . "</li>" ; // BAD!! } That is a good start. Put those two items in two different files and you’ve got some clean separation. Create a class to place that method in and you have a “Model”. Create a simple .php file to put the presentation logic in and you have a “View”, which is very nearly MVC - a common OOP architecture for most frameworks. foo.php <?php $db = new PDO ( 'mysql:host=localhost;dbname=testdb;charset=utf8mb4' , 'username' , 'password' ); // Make your model available include 'models/FooModel.php' ; // Create an instance $fooModel = new FooModel ( $db ); // Get the list of Foos $fooList = $fooModel -> getAllFoos (); // Show the view include 'views/foo-list.php' ; models/FooModel.php <?php class FooModel { protected $db ; public function __construct ( PDO $db ) { $this -> db = $db ; } public function getAllFoos () { return $this -> db -> query ( 'SELECT * FROM table' ); } } views/foo-list.php <?php foreach ( $fooList as $row ) : ?> <li> <?= $row [ 'field1' ] ?> - <?= $row [ 'field1' ] ?> </li> <?php endforeach ?> This is essentially the same as what most modern frameworks are doing, albeit a little more manual. You might not need to do all of that every time, but mixing together too much presentation logic and database interaction can be a real problem if you ever want to unit-test your application. PHPBridge has a great resource called Creating a Data Class which covers a very similar topic, and is great for developers just getting used to the concept of interacting with databases.

Abstraction Layers Many frameworks provide their own abstraction layer which may or may not sit on top of PDO. These will often emulate features for one database system that is missing from another by wrapping your queries in PHP methods, giving you actual database abstraction instead of just the connection abstraction that PDO provides. This will of course add a little overhead, but if you are building a portable application that needs to work with MySQL, PostgreSQL and SQLite then a little overhead will be worth it for the sake of code cleanliness. Some abstraction layers have been built using the PSR-0 or PSR-4 namespace standards so can be installed in any application you like: Aura SQL

Doctrine2 DBAL

Propel

Zend-db

Templating Templates provide a convenient way of separating your controller and domain logic from your presentation logic. Templates typically contain the HTML of your application, but may also be used for other formats, such as XML. Templates are often referred to as “views”, which make up part of the second component of the model–view–controller (MVC) software architecture pattern.

Benefits The main benefit to using templates is the clear separation they create between the presentation logic and the rest of your application. Templates have the sole responsibility of displaying formatted content. They are not responsible for data lookup, persistence or other more complex tasks. This leads to cleaner, more readable code which is especially helpful in a team environment where developers work on the server-side code (controllers, models) and designers work on the client-side code (markup). Templates also improve the organization of presentation code. Templates are typically placed in a “views” folder, each defined within a single file. This approach encourages code reuse where larger blocks of code are broken into smaller, reusable pieces, often called partials. For example, your site header and footer can each be defined as templates, which are then included before and after each page template. Finally, depending on the library you use, templates can offer more security by automatically escaping user-generated content. Some libraries even offer sand-boxing, where template designers are only given access to white-listed variables and functions.

Plain PHP Templates Plain PHP templates are simply templates that use native PHP code. They are a natural choice since PHP is actually a template language itself. That simply means that you can combine PHP code within other code, like HTML. This is beneficial to PHP developers as there is no new syntax to learn, they know the functions available to them, and their code editors already have PHP syntax highlighting and auto-completion built-in. Further, plain PHP templates tend to be very fast as no compiling stage is required. Every modern PHP framework employs some kind of template system, most of which use plain PHP by default. Outside of frameworks, libraries like Plates or Aura.View make working with plain PHP templates easier by offering modern template functionality such as inheritance, layouts and extensions. Simple example of a plain PHP template Using the Plates library. <?php // user_profile.php ?> <? php $this -> insert ( 'header' , [ 'title' => 'User Profile' ]) ?> <h1> User Profile </h1> <p> Hello, <?= $this -> escape ( $name ) ?> </p> <?php $this -> insert ( 'footer' ) ?> Example of plain PHP templates using inheritance Using the Plates library. <?php // template.php ?> < html > < head > < title ><?= $title ?> </title> </head> <body> <main> <?= $this -> section ( 'content' ) ?> </main> </body> </html> <?php // user_profile.php ?> <? php $this -> layout ( 'template' , [ 'title' => 'User Profile' ]) ?> <h1> User Profile </h1> <p> Hello, <?= $this -> escape ( $name ) ?> </p>

Compiled Templates While PHP has evolved into a mature, object oriented language, it hasn’t improved much as a templating language. Compiled templates, like Twig, Brainy, or Smarty*, fill this void by offering a new syntax that has been geared specifically to templating. From automatic escaping, to inheritance and simplified control structures, compiled templates are designed to be easier to write, cleaner to read and safer to use. Compiled templates can even be shared across different languages, Mustache being a good example of this. Since these templates must be compiled there is a slight performance hit, however this is very minimal when proper caching is used. *While Smarty offers automatic escaping, this feature is NOT enabled by default. Simple example of a compiled template Using the Twig library. {% include 'header.html' with {'title': 'User Profile'} %} <h1>User Profile</h1> <p>Hello, {{ name }}</p> {% include 'footer.html' %} Example of compiled templates using inheritance Using the Twig library. // template.html <html> <head> <title>{% block title %}{% endblock %}</title> </head> <body> <main> {% block content %}{% endblock %} </main> </body> </html> // user_profile.html {% extends "template.html" %} {% block title %}User Profile{% endblock %} {% block content %} <h1>User Profile</h1> <p>Hello, {{ name }}</p> {% endblock %}

Errors and Exceptions

Errors In many “exception-heavy” programming languages, whenever anything goes wrong an exception will be thrown. This is certainly a viable way to do things, but PHP is an “exception-light” programming language. While it does have exceptions and more of the core is starting to use them when working with objects, most of PHP itself will try to keep processing regardless of what happens, unless a fatal error occurs. For example: $ php -a php > echo $foo ; Notice: Undefined variable: foo in php shell code on line 1 This is only a notice error, and PHP will happily carry on. This can be confusing for those coming from “exception-heavy” languages, because referencing a missing variable in Python for example will throw an exception: $ python > >> print foo Traceback (most recent call last): File "<stdin> ", line 1, in <module> NameError: name 'foo' is not defined The only real difference is that Python will freak out over any small thing, so that developers can be super sure any potential issue or edge-case is caught, whereas PHP will keep on processing unless something extreme happens, at which point it will throw an error and report it. Error Severity PHP has several levels of error severity. The three most common types of messages are errors, notices and warnings. These have different levels of severity; E_ERROR , E_NOTICE , and E_WARNING . Errors are fatal run-time errors and are usually caused by faults in your code and need to be fixed as they’ll cause PHP to stop executing. Notices are advisory messages caused by code that may or may not cause problems during the execution of the script, execution is not halted. Warnings are non-fatal errors, execution of the script will not be halted. Another type of error message reported at compile time are E_STRICT messages. These messages are used to suggest changes to your code to help ensure best interoperability and forward compatibility with upcoming versions of PHP. Changing PHP’s Error Reporting Behaviour Error Reporting can be changed by using PHP settings and/or PHP function calls. Using the built in PHP function error_reporting() you can set the level of errors for the duration of the script execution by passing one of the predefined error level constants, meaning if you only want to see Errors and Warnings - but not Notices - then you can configure that: <?php error_reporting ( E_ERROR | E_WARNING ); You can also control whether or not errors are displayed to the screen (good for development) or hidden, and logged (good for production). For more information on this check out the Error Reporting section. Inline Error Suppression You can also tell PHP to suppress specific errors with the Error Control Operator @ . You put this operator at the beginning of an expression, and any error that’s a direct result of the expression is silenced. <?php echo @ $foo [ 'bar' ]; This will output $foo['bar'] if it exists, but will simply return a null and print nothing if the variable $foo or 'bar' key does not exist. Without the error control operator, this expression could create a PHP Notice: Undefined variable: foo or PHP Notice: Undefined index: bar error. This might seem like a good idea, but there are a few undesirable tradeoffs. PHP handles expressions using an @ in a less performant way than expressions without an @ . Premature optimization may be the root of all programming arguments, but if performance is particularly important for your application/library it’s important to understand the error control operator’s performance implications. Secondly, the error control operator completely swallows the error. The error is not displayed, and the error is not sent to the error log. Also, stock/production PHP systems have no way to turn off the error control operator. While you may be correct that the error you’re seeing is harmless, a different, less harmless error will be just as silent. If there’s a way to avoid the error suppression operator, you should consider it. For example, our code above could be rewritten like this: <?php //Null Coalescing Operator echo $foo [ 'bar' ] ?? '' ; One instance where error suppression might make sense is where fopen() fails to find a file to load. You could check for the existence of the file before you try to load it, but if the file is deleted after the check and before the fopen() (which might sound impossible, but it can happen) then fopen() will return false and throw an error. This is potentially something PHP should resolve, but is one case where error suppression might seem like the only valid solution. Earlier we mentioned there’s no way in a stock PHP system to turn off the error control operator. However, Xdebug has an xdebug.scream ini setting which will disable the error control operator. You can set this via your php.ini file with the following. xdebug.scream = On You can also set this value at runtime with the ini_set function <?php ini_set ( 'xdebug.scream' , '1' ) The “Scream” PHP extension offers similar functionality to Xdebug’s, although Scream’s ini setting is named scream.enabled . This is most useful when you’re debugging code and suspect an informative error is suppressed. Use scream with care, and as a temporary debugging tool. There’s lots of PHP library code that may not work with the error control operator disabled. Error Control Operators

SitePoint

Xdebug

Scream ErrorException PHP is perfectly capable of being an “exception-heavy” programming language, and only requires a few lines of code to make the switch. Basically you can throw your “errors” as “exceptions” using the ErrorException class, which extends the Exception class. This is a common practice implemented by a large number of modern frameworks such as Symfony and Laravel. In debug mode (or dev mode) both of these frameworks will display a nice and clean stack trace. There are also some packages available for better error and exception handling and reporting. Like Whoops!, which comes with the default installation of Laravel and can be used in any framework as well. By throwing errors as exceptions in development you can handle them better than the usual result, and if you see an exception during development you can wrap it in a catch statement with specific instructions on how to handle the situation. Each exception you catch instantly makes your application that little bit more robust. More information on this and details on how to use ErrorException with error handling can be found at ErrorException Class. Error Control Operators

Predefined Constants for Error Handling

error_reporting()

Reporting

Exceptions Exceptions are a standard part of most popular programming languages, but they are often overlooked by PHP programmers. Languages like Ruby are extremely Exception heavy, so whenever something goes wrong such as a HTTP request failing, or a DB query goes wrong, or even if an image asset could not be found, Ruby (or the gems being used) will throw an exception to the screen meaning you instantly know there is a mistake. PHP itself is fairly lax with this, and a call to file_get_contents() will usually just get you a FALSE and a warning. Many older PHP frameworks like CodeIgniter will just return a false, log a message to their proprietary logs and maybe let you use a method like $this->upload->get_error() to see what went wrong. The problem here is that you have to go looking for a mistake and check the docs to see what the error method is for this class, instead of having it made extremely obvious. Another problem is when classes automatically throw an error to the screen and exit the process. When you do this you stop another developer from being able to dynamically handle that error. Exceptions should be thrown to make a developer aware of an error; they then can choose how to handle this. E.g.: <?php $email = new Fuel\Email ; $email -> subject ( 'My Subject' ); $email -> body ( 'How the heck are you?' ); $email -> to ( 'guy@example.com' , 'Some Guy' ); try { $email -> send (); } catch ( Fuel\Email\ValidationFailedException $e ) { // The validation failed } catch ( Fuel\Email\SendingFailedException $e ) { // The driver could not send the email } finally { // Executed regardless of whether an exception has been thrown, and before normal execution resumes } SPL Exceptions The generic Exception class provides very little debugging context for the developer; however, to remedy this, it is possible to create a specialized Exception type by sub-classing the generic Exception class: <?php class ValidationException extends Exception {} This means you can add multiple catch blocks and handle different Exceptions differently. This can lead to the creation of a lot of custom Exceptions, some of which could have been avoided using the SPL Exceptions provided in the SPL extension. If for example you use the __call() Magic Method and an invalid method is requested then instead of throwing a standard Exception which is vague, or creating a custom Exception just for that, you could just throw new BadMethodCallException; . Read about Exceptions

Read about SPL Exceptions

Nesting Exceptions In PHP

[Exception Best Practices in PHP 5.3][exception-best-practices53]

Security The best resource I’ve found on PHP security is The 2018 Guide to Building Secure PHP Software by Paragon Initiative.

Password Hashing Eventually everyone builds a PHP application that relies on user login. Usernames and passwords are stored in a database and later used to authenticate users upon login. It is important that you properly hash passwords before storing them. Hashing and encrypting are two very different things that often get confused. Hashing is an irreversible, one-way function. This produces a fixed-length string that cannot be feasibly reversed. This means you can compare a hash against another to determine if they both came from the same source string, but you cannot determine the original string. If passwords are not hashed and your database is accessed by an unauthorized third-party, all user accounts are now compromised. Unlike hashing, encryption is reversible (provided you have the key). Encryption is useful in other areas, but is a poor strategy for securely storing passwords. Passwords should also be individually salted by adding a random string to each password before hashing. This prevents dictionary attacks and the use of “rainbow tables” (a reverse list of crytographic hashes for common passwords.) Hashing and salting are vital as often users use the same password for multiple services and password quality can be poor. Additionally, you should use a specialized password hashing algorithm rather than fast, general-purpose cryptographic hash function (e.g. SHA256). The short list of acceptable password hashing algorithms (as of June 2018) to use are: Argon2 (available in PHP 7.2 and newer)

Scrypt

Bcrypt (PHP provides this one for you; see below)

(PHP provides this one for you; see below) PBKDF2 with HMAC-SHA256 or HMAC-SHA512 Fortunately, nowadays PHP makes this easy. Hashing passwords with password_hash In PHP 5.5 password_hash() was introduced. At this time it is using BCrypt, the strongest algorithm currently supported by PHP. It will be updated in the future to support more algorithms as needed though. The password_compat library was created to provide forward compatibility for PHP >= 5.3.7. Below we hash a string, and then check the hash against a new string. Because our two source strings are different (‘secret-password’ vs. ‘bad-password’) this login will fail. <?php require 'password.php' ; $passwordHash = password_hash ( 'secret-password' , PASSWORD_DEFAULT ); if ( password_verify ( 'bad-password' , $passwordHash )) { // Correct Password } else { // Wrong password } password_hash() takes care of password salting for you. The salt is stored, along with the algorithm and “cost”, as part of the hash. password_verify() extracts this to determine how to check the password, so you don’t need a separate database field to store your salts. Learn about password_hash()

password_compat for PHP >= 5.3.7 && < 5.5

for PHP >= 5.3.7 && < 5.5 Learn about hashing in regards to cryptography

Learn about salts

PHP password_hash() RFC

Data Filtering Never ever (ever) trust foreign input introduced to your PHP code. Always sanitize and validate foreign input before using it in code. The filter_var() and filter_input() functions can sanitize text and validate text formats (e.g. email addresses). Foreign input can be anything: $_GET and $_POST form input data, some values in the $_SERVER superglobal, and the HTTP request body via fopen('php://input', 'r') . Remember, foreign input is not limited to form data submitted by the user. Uploaded and downloaded files, session values, cookie data, and data from third-party web services are foreign input, too. While foreign data can be stored, combined, and accessed later, it is still foreign input. Every time you process, output, concatenate, or include data in your code, ask yourself if the data is filtered properly and can it be trusted. Data may be filtered differently based on its purpose. For example, when unfiltered foreign input is passed into HTML page output, it can execute HTML and JavaScript on your site! This is known as Cross-Site Scripting (XSS) and can be a very dangerous attack. One way to avoid XSS is to sanitize all user-generated data before outputting it to your page by removing HTML tags with the strip_tags() function or escaping characters with special meaning into their respective HTML entities with the htmlentities() or htmlspecialchars() functions. Another example is passing options to be executed on the command line. This can be extremely dangerous (and is usually a bad idea), but you can use the built-in escapeshellarg() function to sanitize the executed command’s arguments. One last example is accepting foreign input to determine a file to load from the filesystem. This can be exploited by changing the filename to a file path. You need to remove "/" , "../" , null bytes, or other characters from the file path so it can’t load hidden, non-public, or sensitive files. Learn about data filtering

Learn about filter_var

Learn about filter_input

Learn about handling null bytes Sanitization Sanitization removes (or escapes) illegal or unsafe characters from foreign input. For example, you should sanitize foreign input before including the input in HTML or inserting it into a raw SQL query. When you use bound parameters with PDO, it will sanitize the input for you. Sometimes it is required to allow some safe HTML tags in the input when including it in the HTML page. This is very hard to do and many avoid it by using other more restricted formatting like Markdown or BBCode, although whitelisting libraries like HTML Purifier exists for this reason. See Sanitization Filters Unserialization It is dangerous to unserialize() data from users or other untrusted sources. Doing so can allow malicious users to instantiate objects (with user-defined properties) whose destructors will be executed, even if the objects themselves aren’t used. You should therefore avoid unserializing untrusted data. If you absolutely must unserialize data from untrusted sources, use PHP 7’s allowed_classes option to restrict which object types are allowed to be unserialized. Validation Validation ensures that foreign input is what you expect. For example, you may want to validate an email address, a phone number, or age when processing a registration submission. See Validation Filters

Configuration Files When creating configuration files for your applications, best practices recommend that one of the following methods be followed: It is recommended that you store your configuration information where it cannot be accessed directly and pulled in via the file system.

If you must store your configuration files in the document root, name the files with a .php extension. This ensures that, even if the script is accessed directly, it will not be output as plain text.

extension. This ensures that, even if the script is accessed directly, it will not be output as plain text. Information in configuration files should be protected accordingly, either through encryption or group/user file system permissions.

It is a good idea to ensure that you do not commit configuration files containing sensitive information e.g. passwords or API tokens to source control.

Register Globals NOTE: As of PHP 5.4.0 the register_globals setting has been removed and can no longer be used. This is only included as a warning for anyone in the process of upgrading a legacy application. When enabled, the register_globals configuration setting makes several types of variables (including ones from $_POST , $_GET and $_REQUEST ) available in the global scope of your application. This can easily lead to security issues as your application cannot effectively tell where the data is coming from. For example: $_GET['foo'] would be available via $foo , which can override variables that have been declared. If you are using PHP < 5.4.0 make sure that register_globals is off. Register_globals in the PHP manual

Error Reporting Error logging can be useful in finding the problem spots in your application, but it can also expose information about the structure of your application to the outside world. To effectively protect your application from issues that could be caused by the output of these messages, you need to configure your server differently in development versus production (live). Development To show every possible error during development, configure the following settings in your php.ini : display_errors = On display_startup_errors = On error_reporting = -1 log_errors = On Passing in the value -1 will show every possible error, even when new levels and constants are added in future PHP versions. The E_ALL constant also behaves this way as of PHP 5.4. - php.net The E_STRICT error level constant was introduced in 5.3.0 and is not part of E_ALL , however it became part of E_ALL in 5.4.0. What does this mean? In terms of reporting every possible error in version 5.3 it means you must use either -1 or E_ALL | E_STRICT . Reporting every possible error by PHP version < 5.3 -1 or E_ALL

or 5.3 -1 or E_ALL | E_STRICT

or > 5.3 -1 or E_ALL Production To hide errors on your production environment, configure your php.ini as: display_errors = Off display_startup_errors = Off error_reporting = E_ALL log_errors = On With these settings in production, errors will still be logged to the error logs for the web server, but will not be shown to the user. For more information on these settings, see the PHP manual: error_reporting

display_errors

display_startup_errors

log_errors

Testing Writing automated tests for your PHP code is considered a best practice and can lead to well-built applications. Automated tests are a great tool for making sure your application does not break when you are making changes or adding new functionality and should not be ignored. There are several different types of testing tools (or frameworks) available for PHP, which use different approaches - all of which are trying to avoid manual testing and the need for large Quality Assurance teams, just to make sure recent changes didn’t break existing functionality.

Test Driven Development From Wikipedia: Test-driven development (TDD) is a software development process that relies on the repetition of a very short development cycle: first the developer writes a failing automated test case that defines a desired improvement or new function, then produces code to pass that test and finally refactors the new code to acceptable standards. Kent Beck, who is credited with having developed or ‘rediscovered’ the technique, stated in 2003 that TDD encourages simple designs and inspires confidence. There are several different types of testing that you can do for your application: Unit Testing Unit Testing is a programming approach to ensure functions, classes and methods are working as expected, from the point you build them all the way through the development cycle. By checking values going in and out of various functions and methods, you can make sure the internal logic is working correctly. By using Dependency Injection and building “mock” classes and stubs you can verify that dependencies are correctly used for even better test coverage. When you create a class or function you should create a unit test for each behavior it must have. At a very basic level you should make sure it errors if you send it bad arguments and make sure it works if you send it valid arguments. This will help ensure that when you make changes to this class or function later on in the development cycle that the old functionality continues to work as expected. The only alternative to this would be var_dump() in a test.php, which is no way to build an application - large or small. The other use for unit tests is contributing to open source. If you can write a test that shows broken functionality (i.e. fails), then fix it, and show the test passing, patches are much more likely to be accepted. If you run a project which accepts pull requests then you should suggest this as a requirement. PHPUnit is the de-facto testing framework for writing unit tests for PHP applications, but there are several alternatives atoum

Kahlan

Peridot

SimpleTest Integration Testing From Wikipedia: Integration testing (sometimes called Integration and Testing, abbreviated “I&T”) is the phase in software testing in which individual software modules are combined and tested as a group. It occurs after unit testing and before validation testing. Integration testing takes as its input modules that have been unit tested, groups them in larger aggregates, applies tests defined in an integration test plan to those aggregates, and delivers as its output the integrated system ready for system testing. Many of the same tools that can be used for unit testing can be used for integration testing as many of the same principles are used. Functional Testing Sometimes also known as acceptance testing, functional testing consists of using tools to create automated tests that actually use your application instead of just verifying that individual units of code are behaving correctly and that individual units can speak to each other correctly. These tools typically work using real data and simulating actual users of the application. Selenium

Mink

Codeception is a full-stack testing framework that includes acceptance testing tools

Storyplayer is a full-stack testing framework that includes support for creating and destroying test environments on demand

Behavior Driven Development There are two different types of Behavior-Driven Development (BDD): SpecBDD and StoryBDD. SpecBDD focuses on technical behavior of code, while StoryBDD focuses on business or feature behaviors or interactions. PHP has frameworks for both types of BDD. With StoryBDD, you write human-readable stories that describe the behavior of your application. These stories can then be run as actual tests against your application. The framework used in PHP applications for StoryBDD is Behat, which is inspired by Ruby’s Cucumber project and implements the Gherkin DSL for describing feature behavior. With SpecBDD, you write specifications that describe how your actual code should behave. Instead of testing a function or method, you are describing how that function or method should behave. PHP offers the PHPSpec framework for this purpose. This framework is inspired by the RSpec project for Ruby. Behat, the StoryBDD framework for PHP, inspired by Ruby’s Cucumber project;

PHPSpec, the SpecBDD framework for PHP, inspired by Ruby’s RSpec project;

Codeception is a full-stack testing framework that uses BDD principles.

Servers and Deployment PHP applications can be deployed and run on production web servers in a number of ways.

Platform as a Service (PaaS) PaaS provides the system and network architecture necessary to run PHP applications on the web. This means little to no configuration for launching PHP applications or PHP frameworks. Recently PaaS has become a popular method for deploying, hosting, and scaling PHP applications of all sizes. You can find a list of PHP PaaS “Platform as a Service” providers in our resources section.

Shared Servers PHP has shared servers to thank for its popularity. It is hard to find a host without PHP installed, but be sure it’s the latest version. Shared servers allow you and other developers to deploy websites to a single machine. The upside to this is that it has become a cheap commodity. The downside is that you never know what kind of a ruckus your neighboring tenants are going to create; loading down the server or opening up security holes are the main concerns. If your project’s budget can afford to avoid shared servers, you should. To make sure your shared servers are offering the latest versions of PHP, check out PHP Versions.

Virtualization Running your application on different environments in development and production can lead to strange bugs popping up when you go live. It’s also tricky to keep different development environments up to date with the same version for all libraries used when working with a team of developers. If you are developing on Windows and deploying to Linux (or anything non-Windows) or are developing in a team, you should consider using a virtual machine. This sounds tricky, but besides the widely known virtualization environments like VMware or VirtualBox, there are additional tools that may help you setting up a virtual environment in a few easy steps.

Vagrant Vagrant helps you build your virtual boxes on top of the known virtual environments and will configure these environments based on a single configuration file. These boxes can be set up manually, or you can use “provisioning” software such as Puppet or Chef to do this for you. Provisioning the base box is a great way to ensure that multiple boxes are set up in an identical fashion and removes the need for you to maintain complicated “set up” command lists. You can also “destroy” your base box and recreate it without many manual steps, making it easy to create a “fresh” installation. Vagrant creates folders for sharing your code between your host and your virtual machine, which means that you can create and edit your files on your host machine and then run the code inside your virtual machine. A little help If you need a little help to start using Vagrant there are some services that might be useful: Puphpet: simple GUI to set up virtual machines for PHP development. Heavily focused in PHP . Besides local VMs, it can be used to deploy to cloud services as well. The provisioning is made with Puppet.

. Besides local VMs, it can be used to deploy to cloud services as well. The provisioning is made with Puppet. Protobox: is a layer on top of vagrant and a web GUI to setup virtual machines for web development. A single YAML document controls everything that is installed on the virtual machine.

Phansible: provides an easy to use interface that helps you generate Ansible Playbooks for PHP based projects.

Docker Docker - a lightweight alternative to a full virtual machine - is so called because it’s all about “containers”. A container is a building block which, in the simplest case, does one specific job, e.g. running a web server. An “image” is the package you use to build the container - Docker has a repository full of them. A typical LAMP application might have three containers: a web server, a PHP-FPM process and MySQL. As with shared folders in Vagrant, you can leave your application files where they are and tell Docker where to find them. You can generate containers from the command line (see example below) or, for ease of maintenance, build a docker-compose.yml file for your project specifying which to create and how they communicate with one another. Docker may help if you’re developing multiple websites and want the separation that comes from installing each on it’s own virtual machine, but don’t have the necessary disk space or the time to keep everything up to date. It’s efficient: the installation and downloads are quicker, you only need to store one copy of each image however often it’s used, containers need less RAM and share the same OS kernel, so you can have more servers running simultaneously, and it takes a matter of seconds to stop and start them, no need to wait for a full server boot. Example: Running your PHP Applications in Docker After installing docker on your machine, you can start a web server with one command. The following will download a fully functional Apache installation with the latest PHP version, map /path/to/your/php/files to the document root, which you can view at http://localhost:8080 : docker run -d --name my-php-webserver -p 8080:80 -v /path/to/your/php/files:/var/www/html/ php:apache This will initialize and launch your container. -d makes it runs in the background. To stop and start it, simply run docker stop my-php-webserver and docker start my-php-webserver (the other parameters are not needed again). Learn more about Docker The command above shows a quick way to run a basic server. There’s much more you can do (and thousands of pre-built images in the Docker Hub). Take time to learn the terminology and read the Docker User Guide to get the most from it, and don’t run random code you’ve downloaded without checking it’s safe – unofficial images may not have the latest security patches. If in doubt, stick to the official repositiories. The PHPDocker.io site will auto-generate all the files you need for a fully-featured LAMP/LEMP stack, including your choice of PHP version and extensions. Docker Website

Docker Installation

Docker User Guide

Docker Hub

Docker Hub - official images

Caching PHP is pretty quick by itself, but bottlenecks can arise when you make remote connections, load files, etc. Thankfully, there are various tools available to speed up certain parts of your application, or reduce the number of times these various time-consuming tasks need to run.

Opcode Cache When a PHP file is executed, it must first be compiled into opcodes (machine language instructions for the CPU). If the source code is unchanged, the opcodes will be the same, so this compilation step becomes a waste of CPU resources. An opcode cache prevents redundant compilation by storing opcodes in memory and reusing them on successive calls. It will typically check signature or modification time of the file first, in case there have been any changes. It’s likely an opcode cache will make a significant speed improvement to your application. Since PHP 5.5 there is one built in - Zend OPcache. Depending on your PHP package/distribution, it’s usually turned on by default - check opcache.enable and the output of phpinfo() to make sure. For earlier versions there’s a PECL extension. Read more about opcode caches: Zend OPcache (bundled with PHP since 5.5)

Zend OPcache (formerly known as Zend Optimizer+) is now open source

APC - PHP 5.4 and earlier

XCache

WinCache (extension for MS Windows Server)

list of PHP accelerators on Wikipedia

Object Caching There are times when it can be beneficial to cache individual objects in your code, such as with data that is expensive to get or database calls where the result is unlikely to change. You can use object caching software to hold these pieces of data in memory for extremely fast access later on. If you save these items to a data store after you retrieve them, then pull them directly from the cache for following requests, you can gain a significant improvement in performance as well as reduce the load on your database servers. Many of the popular bytecode caching solutions let you cache custom data as well, so there’s even more reason to take advantage of them. APCu, XCache, and WinCache all provide APIs to save data from your PHP code to their memory cache. The most commonly used memory object caching systems are APCu and memcached. APCu is an excellent choice for object caching, it includes a simple API for adding your own data to its memory cache and is very easy to setup and use. The one real limitation of APCu is that it is tied to the server it’s installed on. Memcached on the other hand is installed as a separate service and can be accessed across the network, meaning that you can store objects in a hyper-fast data store in a central location and many different systems can pull from it. Note that when running PHP as a (Fast-)CGI application inside your webserver, every PHP process will have its own cache, i.e. APCu data is not shared between your worker processes. In these cases, you might want to consider using memcached instead, as it’s not tied to the PHP processes. In a networked configuration APCu will usually outperform memcached in terms of access speed, but memcached will be able to scale up faster and further. If you do not expect to have multiple servers running your application, or do not need the extra features that memcached offers then APCu is probably your best choice for object caching. Example logic using APCu: <?php // check if there is data saved as 'expensive_data' in cache $data = apc_fetch ( 'expensive_data' ); if ( $data === false ) { // data is not in cache; save result of expensive call for later use apc_add ( 'expensive_data' , $data = get_expensive_data ()); } print_r ( $data ); Note that prior to PHP 5.5, APC provides both an object cache and a bytecode cache. APCu is a project to bring APC’s object cache to PHP 5.5+, since PHP now has a built-in bytecode cache (OPcache). Learn more about popular object caching systems: APCu

APC Functions

Memcached

Redis

XCache APIs

WinCache Functions

Documenting your Code

PHPDoc PHPDoc is an informal standard for commenting PHP code. There are a lot of different tags available. The full list of tags and examples can be found at the PHPDoc manual. Below is an example of how you might document a class with a few methods; <?php /** * @author A Name <a.name@example.com> * @link http://www.phpdoc.org/docs/latest/index.html */ class DateTimeHelper { /** * @param mixed $anything Anything that we can convert to a \DateTime object * * @throws \InvalidArgumentException * * @return \DateTime */ public function dateTimeFromAnything ( $anything ) { $type = gettype ( $anything ); switch ( $type ) { // Some code that tries to return a \DateTime object } throw new \InvalidArgumentException ( "Failed Converting param of type ' { $type } ' to DateTime object" ); } /** * @param mixed $date Anything that we can convert to a \DateTime object * * @return void */ public function printISO8601Date ( $