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feature #3686 Documentation of the new PSR-4 class loader. (derrabus)

This PR was merged into the master branch.

Discussion
----------

Documentation of the new PSR-4 class loader.

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes (symfony/symfony#10100)
| Applies to    | 2.5+
| Fixed tickets | #3655

Hello docs team,

this is a first draft of a documentation for the PSR-4 class loaded I've contributed. As this is my first contribution to the documentation, any assistance would be appreciated. :-)

Commits
-------

cb2be4a Moved versionadded block to the top.
16fead4 Adjustments from comments by @bicpi
a05da41 Minor corrections.
6f2a1a3 Adjustments from comments be @wouterj
17166bd First shot of a documentation of the new PSR-4 class loader.
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weaverryan committed Mar 18, 2014
2 parents cd6d1de + cb2be4a commit 3731e2ec5734be3e674cfd6989a8e5f2f01caffb
Showing with 69 additions and 0 deletions.
  1. +1 −0 components/class_loader/index.rst
  2. +67 −0 components/class_loader/psr4_class_loader.rst
  3. +1 −0 components/map.rst.inc
@@ -6,6 +6,7 @@ ClassLoader
introduction
class_loader
psr4_class_loader
map_class_loader
cache_class_loader
debug_class_loader
@@ -0,0 +1,67 @@
.. index::
single: ClassLoader; PSR-4 Class Loader
The PSR-4 Class Loader
======================
.. versionadded:: 2.5
The :class:`Symfony\\Component\\ClassLoader\\Psr4ClassLoader` was
introduced in Symfony 2.5.
Libraries that follow the `PSR-4`_ standard can be loaded with the ``Psr4ClassLoader``.
.. note::
If you manage your dependencies via Composer, you get a PSR-4 compatible
autoloader out of the box. Use this loader in environments where Composer
is not available.
.. tip::
All Symfony components follow PSR-4.
Usage
-----
The following example demonstrates how you can use the
:class:`Symfony\\Component\\ClassLoader\\Psr4ClassLoader` autoloader to use
Symfony's Yaml component. Imagine, you downloaded both the ClassLoader and
Yaml component as ZIP packages and unpacked them to a ``libs`` directory.
The directory structure will look like this:
.. code-block:: text
libs/
ClassLoader/
Psr4ClassLoader.php
...
Yaml/
Yaml.php
...
config.yml
demo.php
In ``demo.php`` you are going to parse the ``config.yml`` file. To do that, you
first need to configure the ``Psr4ClassLoader``:
.. code-block:: php
use Symfony\Component\ClassLoader\Psr4ClassLoader;
use Symfony\Component\Yaml\Yaml;
require __DIR__.'/lib/ClassLoader/Psr4ClassLoader.php';
$loader = new Psr4ClassLoader();
$loader->addPrefix('Symfony\\Component\\Yaml\\', __DIR__.'/lib/Yaml');
$loader->register();
$data = Yaml::parse(__DIR__.'/config.yml');
First of all, the class loader is loaded manually using a ``require``
statement, since there is no autoload mechanism yet. With the
:method:`Symfony\Component\ClassLoader\Psr4ClassLoader::addPrefix` call, you
tell the class loader where to look for classes with the
``Symfony\Component\Yaml\`` namespace prefix. After registering the autoloader,
the Yaml component is ready to be used.
.. _PSR-4: http://www.php-fig.org/psr/psr-4/
@@ -4,6 +4,7 @@
* :doc:`/components/class_loader/introduction`
* :doc:`/components/class_loader/class_loader`
* :doc:`/components/class_loader/psr4_class_loader`
* :doc:`/components/class_loader/map_class_loader`
* :doc:`/components/class_loader/cache_class_loader`
* :doc:`/components/class_loader/debug_class_loader`

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