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PSR Compliance
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The `PHP-FIG <https://www.php-fig.org/>`_ was created in 2009 to help make code more interoperable between frameworks
by ratifying Interfaces, style guides, and more that members were free to implement or not. While CodeIgniter is
not a member of the FIG, we are compatible with a number of their proposals. This guide is meant to list the
status of our compliance with the various accepted, and some draft, proposals.

**PSR-1: Basic Coding Standard**

This recommendation covers basic class, method, and file-naming standards. Our
`style guide <https://github.com/codeigniter4/CodeIgniter4/blob/develop/contributing/styleguide.rst>`_
meets PSR-1 and adds its own requirements on top of it.

**PSR-2: Coding Style Guide**

This PSR was fairly controversial when it first came out. CodeIgniter meets many of the recommendations within,
but does not, and will not, meet all of them.

**PSR-3: Logger Interface**

CodeIgniter's :doc:`Logger </general/logging>` implements all of the interfaces provided by this PSR.

**PSR-4: Autoloading Standard**

This PSR provides a method for organizing file and namespaces to allow for a standard method of autoloading
classes. Our :doc:`Autoloader </concepts/autoloader>` meets the PSR-4 recommendations.

**PSR-6: Caching Interface**

CodeIgniter will not be trying to meet this PSR, as we believe it oversteps its needs. The newly proposed
`SimpleCache Interfaces <https://github.com/dragoonis/fig-standards/blob/psr-simplecache/proposed/simplecache.md>`_
do look like something we would consider.

**PSR-7: HTTP Message Interface**

This PSR standardizes a way of representing the HTTP interactions. While many of the concepts became part of our
HTTP layer, CodeIgniter does not strive for compatibility with this recommendation.

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If you find any places that we claim to meet a PSR but have failed to execute it correctly, please let us know
and we will get it fixed, or submit a pull request with the required changes.
