gistfile1.md

PSR-4: Class Autoloading

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

1. Introduction

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The goal for this specification is to extend PSR-0 and to provide an alternative option for applications to determine the location of a file resource on a medium as supported by PHP, when a fully-qualified class name is provided.

2. Scope

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This specification is partly backwards incompatible with PSR-0. Where a conflict occurs the rules in this specification precede, or override, the rules in PSR-0.

3. Specification

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• The _ character has no special meaning in class names.
• For a collection of one or more classes a namespace prefix MUST be documented.
• The documented namespace prefix MUST be a valid namespace for each class in the collection.
• The portion of the fully-qualified class name following the namespace prefix must be considered the fully-qualified class name for the purpose of transformation into a filename.
• A conforming autoloader MUST NOT interfere with other autoloaders, and as such it MUST NOT throw exceptions, MUST NOT raise errors of any level, and SHOULD NOT return a value.

4. Examples

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• Given a namespace prefix \Doctrine\Common and a fully-qualified class name \Doctrine\Common\IsolatedClassLoader, the resulting filename would be IsolatedClassLoader.php.
• Given a namespace prefix \Doctrine and a fully-qualified class name \Doctrine\Common\IsolatedClassLoader, the resulting filename would be Common/IsolatedClassLoader.php.
• Given a namespace prefix \Symfony\Component\HttpFoundation and a fully-qualified class name \Symfony\Component\HttpFoundation\Request, the resulting filename would be Request.php.
• Given a namespace prefix \Symfony and a fully-qualified class name \Symfony\Component\HttpFoundation\Request, the resulting filename would be Component/HttpFoundation/Request.php.
• Given a namespace prefix \Zend and a fully-qualified class name \Zend\Acl, the resulting filename would be Acl.php.
• Given a namespace prefix \Acme\My_Project and a fully-qualified class name \Acme\My_Project\Some_module\some_class, the resulting filename would be Some_module/some_class.php.

With a nod to @simensen I present this alternative rewrite of the alternative rewrite: https://gist.github.com/pmjones/7129733

@philsturgeon - the examples here are more like test cases. I believe they serve to illustrate expected input/output.

I don't know how anyone could not understand the rules. Clearly everyone got PSR0 without any misunderstanding so this document is just PSR0 with a few amendments. PSR0 is already understood, so therefore amendment is simple to follow.