gistfile1.php

<?php
//http://d.hatena.ne.jp/technohippy/20081121#1227285803

class Acme_ArrayOrdinalAccesser implements ArrayAccess {
    
    public function __construct(array $array) {
        foreach($array as $k => $v ) $this->offsetSet($k, $v);
    }

    public function __set($offset, $value) {
        $this->offsetSet($offset, $value);
    }
    
    public function __get($offset) {
        return $this->offsetGet($offset);
    }
    
    public function offsetExists( $offset ) {
        return isset( $this->$offset );
    }

    public function offsetSet( $offset, $value)
    {
        if (!is_null($k = $this->map($offset))) {
            $this[$k] = $value;
        } else {
            $this->$offset = $value;
        }
        
    }

    public function offsetGet( $offset )
    {
        if (!is_null($k = $this->map($offset))) {
            return $this[$k];
        } else {
            return $this->$offset;
        }
    }

    public function offsetUnset( $offset ) {
        unset( $this->$offset );
    }
    
    private function map($offset) {
    
        $LESS_THAN_20 = array(
            'zero',    'one',     'two',       'three',    'four',
            'five',    'six',     'seven',     'eight',    'nine',
            'ten',     'eleven',  'twelve',    'thirteen', 'fourteen',
            'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'
        );
        
        $DOUBLE_FIGURES = array(
         null,    'ten',   'twenty',  'thirty', 'forty',
        'fifty', 'sixty', 'seventy', 'eighty', 'ninety'
        );
        
        $key20 = array_flip($LESS_THAN_20);
        
        if (array_key_exists($offset, $key20)) {
            return $key20[$offset] - 1;
        } else {
            return null;
        }
        
    }
}
if (debug_backtrace()) {return;}
$array = new Acme_ArrayOrdinalAccesser(range(1,10));
    //print_r($array);
$array->nine = 'NINE';
print_r((array)$array);
/**
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
    [6] => 7
    [7] => 8
    [8] => NINE
    [9] => 10
)
*/