One Class Per File

One class per file makes it easy to find class definitions in the file system. It is confusing to search for class A in B.php file, as they are both in the same file. Version control log messages are also either to read.

It also help to follow PSR-0 to PSR-4 recommendations and automate class loading with namespaces and autoload.

Rule Details

This rule require that every class is defined in a file, and that every file that defines a class only hold one. The following patterns are considered warnings:

<?php

class a { /**/ }

class b extends a { /**/ }

?>

The following code is considered legit :

<?php

class a { /**/ }
?>

Another file :

<?php

class b extends a { /**/ }

?>

When Not To Use It

If you have some mechanism that compile all classes into one file for faster loading, this rule may be ignore for that kind of file.