Psr4 Class Naming

ID

php.psr4_class_naming

Severity

info

Remediation Complexity

trivial

Remediation Risk

medium

Remediation Effort

low

Resource

Naming Convention

Language

Php

Tags

autoloading, naming_convention

Description

Reports a class, interface, trait or enum whose name does not match the base name of the file that declares it, as required by the PSR-0 / PSR-4 autoloading standards. A file Foo.php must declare exactly one type, named Foo, compared case-sensitively. Any extra top-level type, and any sole type whose name differs from the file base name, breaks autoloading.

Rationale

PSR-4 maps a fully-qualified class name directly onto a file path, so the autoloader expects the type App\Foo in Foo.php. A type named differently from its file, or a second type sharing the file, cannot be found by the standard autoloader and forces a manual require — defeating the point of autoloading and making the codebase harder to navigate. Because at most one type can match the file base name, the matching type is left alone and the mismatched or extra types are flagged. Anonymous classes have no name and are never reported. Files that are not PSR-4 autoloaded are exempt: WordPress-style class-.php / interface-.php / trait-*.php files, timestamped Laravel migrations under a migrations/ directory, and test files (*Test / *Tests).

<?php
// File: Order.php
class Order {}        // OK — name matches the file base name

class OrderHelper {}  // FLAW — extra type in Order.php; belongs in OrderHelper.php

Remediation

Move each type into its own file whose base name matches the type name exactly (case-sensitive), e.g. place OrderHelper in OrderHelper.php. Rename a sole mismatched type, or its file, so the two agree.

References