ArrayAccess example from php.net

ArrayAccessExample.php

<?php
class obj implements arrayaccess {
    private $container = array();
    
    //設定 $container
    public function __construct() {
        $this->container = array(
            "one"   => 1,
            "two"   => 2,
            "three" => 3,
        );
    }

    //設定 $container[$offset] = $value
    //$offset未指定時則以數字索引賦值
    public function offsetSet($offset, $value) {
        if (is_null($offset)) {
            $this->container[] = $value;
        } else {
            $this->container[$offset] = $value;
        }
    }

    //檢查$container[$offset]是否有值，回傳true false
    public function offsetExists($offset) {
        return isset($this->container[$offset]);
    }

    //unset $container[$offset]
    public function offsetUnset($offset) {
        unset($this->container[$offset]);
    }

    //取得$container[$offset]之值回傳
    public function offsetGet($offset) {
        return isset($this->container[$offset]) ? $this->container[$offset] : null;
    }
}

/*
*    此時 $obj 為一個物件
*    其 container 屬性為陣列 ['one' => 1, 'two' => 2, 'three' => 3]
*
*/
$obj = new obj;

var_dump(isset($obj["two"])); // bool(true)
var_dump($obj["two"]); // int(2)
unset($obj["two"]);
var_dump(isset($obj["two"])); // bool(false)
$obj["two"] = "A value";
var_dump($obj["two"]); // string(7) "A value"
$obj[] = 'Append 1'; // $obj->container[0] = 'Append 1'
$obj[] = 'Append 2'; // $obj->container[1] = 'Append 2'
$obj[] = 'Append 3'; // $obj->container[2] = 'Append 3'
print_r($obj);

//obj Object
//(
//    [container:obj:private] => Array
//        (
//            [one] => 1
//            [three] => 3
//            [two] => A value
//            [0] => Append 1
//            [1] => Append 2
//            [2] => Append 3
//        )
//)


?>