//看个例子 class My{ private $_data = [ 'a' => '燕睿涛', 'b' => 'yanruitao', 'c' => 'LULU', ]; public function getIterator() { return new ArrayIterator($this->_data); } } $obj = new My; foreach ($obj as $key => $value) { echo "$key => $value\n"; } //输出结果为空 class My implements IteratorAggregate { private $_data = [ 'a' => '燕睿涛', 'b' => 'yanruitao', 'c' => 'LULU', ]; public function getIterator() { return new ArrayIterator($this->_data); } } $obj = new My; foreach ($obj as $key => $value) { echo "$key => $value\n"; } //结果: a => 燕睿涛 b => yanruitao c => LULU Countable Countable { abstract public int count(void) }
class CountMe { protected $_myCount = 3; public function count() { return $this->_myCount; } } $countable = new CountMe(); echo count($countable); //返回1 class CountMe implements Countable { protected $_myCount = 3; public function count() { return $this->_myCount; } } $countable = new CountMe(); echo count($countable); //返回3 ArrayAccess ArrayAccess { abstract public boolean offsetExists(mixed $offset) abstract public mixed offsetGet(mixed $offset) public void offsetSet(mixed $offset, mixed $value) public void offsetUnset(mixed $offset) }
class myObj { } $obj = new myObj; $obj['name']; //Fatal error: Cannot use object of type myObj as array in class myObj implements ArrayAccess { public function offsetSet($offset, $value) { echo "offsetSet : {$offset} => {$value}\n"; } public function offsetExists($offset) { echo "offsetExists : {$offset}\n"; } public function offsetUnset($offset) { echo "offsetUnset : {$offset}\n"; } public function offsetGet($offset) { echo "offsetGet : {$offset}\n"; } } $obj = new myObj; $obj[1] = '燕睿涛'; isset($obj['name']); unset($obj['name']); $obj['yrt']; //输出结果: offsetSet : 1 => 燕睿涛 offsetExists : name offsetUnset : name offsetGet : yrt class myObj implements ArrayAccess { private $_data = []; public function offsetSet($offset, $value) { $this->_data[$offset] = $value; } public function offsetExists($offset) { return isset($this->_data[$offset]); } public function offsetUnset($offset) { unset($this->_data[$offset]); } public function offsetGet($offset) { return $this->_data[$offset]; } } $obj = new myObj; $obj['yrt'] = '燕睿涛'; var_dump($obj['yrt']); var_dump(isset($obj['yrt'])); unset($obj['yrt']); var_dump(isset($obj['yrt'])); var_dump($obj['yrt']); //输出: string(9) "燕睿涛" bool(true) bool(false) Notice: Undefined index: yrt //最后一个会报出Notice 上面的对象只能是基本的数组操作,连遍历都不行,结合之前的IteratorAggregate可以进行foreach: class myObj implements ArrayAccess, IteratorAggregate { private $_data = []; public function getIterator() { return new ArrayIterator($this->_data); } ...... } $obj = new myObj; $obj['yrt'] = '燕睿涛'; $obj[1] = '燕睿涛'; $obj['name'] = '燕睿涛'; $obj['age'] = 23; foreach ($obj as $key => $value) { echo "{$key} => {$value}\n"; } //输出: yrt => 燕睿涛 1 => 燕睿涛 name => 燕睿涛 age => 23 Iterator Iterator extends Traversable { abstract public mixed current(void) abstract public scalar key(void) abstract public void next(void) abstract public void rewind(void) abstract public boolean valid(void) }
class myObj implements Iterator{ private $_data = []; public function __construct(Array $arr) { $this->_data = $arr; } public function current() { return current($this->_data); } public function key() { return key($this->_data); } public function next() { next($this->_data); } public function rewind() { reset($this->_data); } public function valid() { return $this->key() !== NULL; } } $t = [ 'yrt' => '燕睿涛', 'name' => '燕睿涛', false, '燕睿涛' ]; $obj = new myObj($t); foreach ($obj as $key => $value) { echo "{$key} => ".var_export($value, true)."\n"; } //输出: yrt => '燕睿涛' name => '燕睿涛' 0 => false 1 => '燕睿涛'