Rudd-O.com

As it turns out, version 0.7 of the runkit extension for PHP has problems when copying methods from a class into another. Of course, this punts my original multiple inheritance simulation technique. The bug in detail: copying of methods from “parent” classes into the “child” class succeeds, but later on, when attempting to use a method, PHP requests ludicrous amounts of memory to the OS, which causes PHP to fail.

In lieu of that problem, I decided to explore alternatives. The final, usable alternative seems to be:

function inherits_from($destClassName,$srcClassNameList) {
    foreach ($srcClassNameList as $s) {
        runkit_class_adopt($destClassName,$s);
    }
}

And this version does work without the memory exhaustion problem. In short:

<?php

class A { ...A's methods here... }

class B { ...B's methods here... }

class C { ...C's methods here... }

class MultipleInheritedClass { ...this class' methods here... } inherits_from( 'MultipleInheritedClass', array('A','B','C') ); ?>

The inherits_from construct does the magic. All you need to type there is:

• The name of the “child” class
• An array containing the names of the “parent” classes

Of course, this technique works only in PHP 5, with the runkit extension.

Despite the cutting-edge requirements, I’ve just shown there’s a practical way to build multiple inheritance in PHP. Mixin classes, aggregate classes, they’re a few keystrokes away. Long live PHP!

Oh, by the way, did I mention that I built convenient RPM packages of runkit?

This entry was posted on Saturday, March 18th, 2006 at 9:42 and is filed under PHP, Programming, Software bacán. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.