AbstractClassExample.php

<?php

abstract class Debugger
{
    abstract public function debug($message);
}

class BrowserDebugger extends Debugger
{
    public function debug($message)
    {
        echo "<pre>";
        print_r($message);
        echo "</pre>";
    }
}

class CLIDebugger extends Debugger
{
    public function debug($message)
    {
        print_r($message);
    }
}

$debugger = new CLIDebugger();
$debugger->debug(array('foo' => 'bar'));

$debugger = new BrowserDebugger();
$debugger->debug(array('foo' => 'bar'));