The ArrayAccess interface

1. 接口内容

   ArrayAccess {
    /* Methods */
    abstract public offsetExists ( mixed $offset ) : bool
    abstract public offsetGet ( mixed $offset ) : mixed
    abstract public offsetSet ( mixed $offset , mixed $value ) : void
    abstract public offsetUnset ( mixed $offset ) : void
   }

2. 案例

   <?php
   class Obj implements ArrayAccess {
    private $container = array();
    public function __construct() {
        $this->container = array(
            "one"   => 1,
            "two"   => 2,
            "three" => 3,
        );
    }
   
    public function offsetSet($offset, $value) {
        if (is_null($offset)) {
            $this->container[] = $value;
        } else {
            $this->container[$offset] = $value;
        }
    }
   
    public function offsetExists($offset) {
        return isset($this->container[$offset]);
    }
   
    public function offsetUnset($offset) {
        unset($this->container[$offset]);
    }
   
    public function offsetGet($offset) {
        return isset($this->container[$offset]) ? $this->container[$offset] : null;
    }
   }
   $obj = new Obj;
   var_dump(isset($obj["two"]));
   var_dump($obj["two"]);
   unset($obj["two"]);
   var_dump(isset($obj["two"]));
   $obj["two"] = "A value";
   var_dump($obj["two"]);
   $obj[] = 'Append 1';
   $obj[] = 'Append 2';
   $obj[] = 'Append 3';
   print_r($obj);
   ?>

3. 案例结果

    bool(true)
    int(2)
    bool(false)
    string(7) "A value"
    obj Object
    (
        [container:obj:private] => Array
            (
                [one] => 1
                [three] => 3
                [two] => A value
                [0] => Append 1
                [1] => Append 2
                [2] => Append 3
            )
    )

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