Mixin.php

<?php  // vim: ts=4 sts=4 sw=4

class Mixin
{
    private $mixins = array( );
    private $strict = false;

    function __construct ($include=array( ))
    {
        if ( !is_array($include) ) {
            trigger_error('Invalid Argument', E_USER_ERROR);
        }

        if ( $key = array_search('__strict', $include) ) {
            $this->strict = true;
            unset( $include[$key] );
        }

        foreach ($include as $inc) {
            $inc = is_object($inc)
                 ? $inc
                 : new $inc;

            $this->mixin($inc);
        }
    }

    function __call ($func, $args)
    {
        if ( array_key_exists($func, $this->mixins) ) {
            $class = array($this->mixins[$func], $func);
            return call_user_func_array($class, $args);
        }

        trigger_error('Call to undefinded function: '.$func, E_USER_ERROR);
    }

    private function mixin ($obj)
    {
        $methods = get_class_methods($obj);
        foreach ($methods as $m) {
            if ( array_key_exists($m, $this->mixins) && $this->strict ) {
                trigger_error("Cannot redeclare $m", E_USER_ERROR);
            }
            else if ( !preg_match('/^__/', $m) ) {
                $this->mixins[$m] =& $obj;
            }
        }
    }
}