php中,foreach可以很方便地对可迭代结构(例如数组,再如对象)进行迭代操作:
[php] view plaincopy
foreach( $array as $elem){
var_dump($elem);
}
[php] view plaincopy
foreach($obj as $key=>$value){
echo "$key=>$value".PHP_EOL;
}
因而我们想:如果对于一个实例化对象,对其进行foreach操作,会发生什么事情呢?
首先我们定义的基础类为:
[php] view plaincopy
Class Test{
/* one public variable */
public $a;
public $b;
/* one private variable */
private $c;
public function __construct(){
$this->a = "public";
$this->b = "public";
$this->c = "private";
}
public function traverseInside(){
foreach($this as $key=>$value){
echo $key."=>".$value.EOL;
}
}
}
然后我们实例化该类,对其进行迭代,并与内部迭代的结果进行比较:
[php] view plaincopy
$test = new Test;
echo "";
echo "traverse outside:".EOL;
foreach( $test as $key=>$value ){
echo $key."=>".$value.EOL;
}
echo "";
echo "traverse inside:".EOL;
$test->traverseInside();
迭代的结果为:
可以看出:外部foreach循环的结果,只是将对象的公有属性(public)循环出来了,而对于私有属性(private),外部foreach是无法循环出来的。因而我们如果想要在外部通过foreach循环出类的所有的属性(公有的和私有的),仅仅依靠foreach是不行的,必须要对类进行“改造”。如何对类进行改造呢?如果你了解foreach的实现收起↑
php中,foreach可以很方便地对可迭代结构(例如数组,再如对象)进行迭代操作:
[php] view plaincopy
foreach( $array as $elem){
var_dump($elem);
}
[php] view plaincopy
foreach($obj as ...展开↓