Autoloading in PHP

Why & How

- magical function __autoload 

http://php.net/manual/en/function.autoload.php

- Before PHP 5.3: PEAR Coding Standard

http://pear.php.net/manual/en/standards.naming.php

Example: 'Zend_Db_Table' => 'Zend/Db/Table.php'

- From PHP 5.3: Namespace

http://php.net/manual/en/language.namespaces.php

PSR-0: Autoloading Standard

http://www.php-fig.org/psr/psr-0/

- Structure:

\<Vendor Name>\(<Namespace>\)*<Class Name>

- Namespace separator is converted to DIRECTORY_SEPARATOR when loading

- Backwards compatibility for PEAR-standard classnames

Examples

\Symfony\Core\Request => /path/to/project/lib/vendor/Symfony/Core/Request.php

\namespace\package_name\Class_Name => /path/to/project/lib/vendor/namespace/package_name/Class/Name.php

Problems

vendor/
    vendor_name/
        package_name/
            src/
                Vendor_Name/
                    Package_Name/
                        ClassName.php       # Vendor_Name\Package_Name\ClassName
            tests/
                Vendor_Name/
                    Package_Name/
                        ClassNameTest.php   # Vendor_Name\Package_Name\ClassNameTest
vendor/
    vendor_name/
        package_name/
            src/
                Vendor_Name/
                    Package_Name/
                        ClassName.php       # Vendor_Name\Package_Name\ClassName
            tests/
                Vendor_Name/
                    Package_Name/
                        ClassNameTest.php   # Vendor_Name\Package_Name\ClassNameTest

Sometimes folder structure becomes too deep and duplicated, especially when using with Composer

PSR-4: Improved Autoloading

vendor/
    vendor_name/
        package_name/
            src/
                ClassName.php       # Vendor_Name\Package_Name\ClassName
            tests/
                ClassNameTest.php   # Vendor_Name\Package_Name\ClassNameTest

- Allow a more concise folder structure

- Drop backwards compatibility

- For now PSR-0 is officially deprecated

http://www.php-fig.org/psr/psr-4/

Examples

Problems

Do not show the exact path of a class (opposed to PSR-0)

Composer

What is Composer?

- A tool for dependency management in PHP

1. You have a project that depends on a number of libraries

2. Some of those libraries depend on other libraries

3. You declare the things you depend on

=> Composer finds out which versions of which packages need to be installed, and downloads them into your project

Why Composer?

- Avoid reinventing the wheel

- Third-party manager for dependencies

- Easy to use?

- Composer vs PEAR

Install

Local:

curl -sS https://getcomposer.org/installer | php

To use Composer, run: 

php composer.phar

Global:

curl -sS https://getcomposer.org/installer | php

mv composer.phar /usr/local/bin/composer

To use Composer, run:

composer

composer.json

- Setup project: define all dependencies

- Located in project root directory

{
    "require": {
	"laravel/framework": "4.0.*"
    }
}

Packagist

https://packagist.org/ - the main Composer repository

Installing dependencies

composer install

- Create composer.lock 

-  Each installed package will have a package definition located in its root directory

composer.lock

- The lock file: list versions of all installed packages

- Created by composer install,  updated by composer update

- Both composer.json and composer.lock should be stored in version control

Autoloading

- Composer helps to set up autoloading

<?php
require 'vendor/autoload.php'; // include this in your bootstrap process

- Define our autoloader in composer.json

{
    "require": {...},
    "autoload": {
        "psr-4": {"MyApp\\": "src/"}
    }
}