1，魔术方法__set与__get, __call
>这些魔术方法，将在相关的属性或者方法不存在时调用
>函数原型
.function __set( $property, $value )：传递属性的名字和新的值
.function __get( $property )：传递属性的名字，并且返回属性的值
.function __call( $methods, $args )：传递方法的名字和一个数字索引的数组，数组包含传递的参数，第一个参数的索引是0
1 class Coordinate { 2 ????????private $arr = array( ‘x‘ => null, ‘y‘ => null ); 3 ????????function __get( $property ) { 4 ????????????if( array_key_exists( $property, $this->arr ) ){ 5 ????????????????return $this->arr[$property]; 6 ????????????}else { 7 ????????????????print "不能访问一个不存在的键名" . PHP_EOL; 8 ????????????} 9 ????????}10 ????????function __set( $property, $value ) {11 ????????????if( array_key_exists( $property, $this->arr ) ) {12 ????????????????$this->arr[$property] = $value;13 ????????????}else {14 ????????????????print "不能设置一个不存在的键名" . PHP_EOL;15 ????????????}16 ????????}17 ????}18 ????19 ????$obj = new Coordinate();20 ????$obj->x = 10;21 ????echo $obj->x . PHP_EOL;22 ????$obj->n = 20;23 ????echo $obj->n . PHP_EOL;2，__call的应用
>通过__call可以使HelloWorldDelegator的实例调用HelloWorld的任意存在的方法
1 class HelloWorld { 2 ????????function display( $count ){ 3 ????????????for( $i = 0 ; $i < $count; $i++ ) { 4 ????????????????echo "Hello World $i " . PHP_EOL; 5 ????????????} 6 ????????????return $count; 7 ????????} 8 ????} 9 10 ????11 ????class HelloWorldDelegator {12 ????????private $obj;13 ????????function __construct(){14 ????????????$this->obj = new HelloWorld();15 ????????}16 ????????function __call( $method, $args ) {17 ????????????return call_user_func_array( array( $this->obj, $method ), $args );18 ????????}19 ????}20 21 ????$obj = new HelloWorldDelegator();22 ????print $obj->display( 3 );23 ????print PHP_EOL;24 ????25 ????$obj->show();3，迭代
>实现一个自己的迭代器，可以通过实现Iterator接口
Iterator接口原型：
Iterator extends Traversable {/* Methods */abstract public mixed current ( void )abstract public scalar key ( void )abstract public void next ( void )abstract public void rewind ( void )abstract public bool valid ( void )} 1 class NumberSquared implements Iterator { 2 ????private $start; 3 ????private $end; 4 ????private $cur; 5 ?6 ????function __construct ( $start, $end ){ 7 ????????$this->start = $start; 8 ????????$this->end = $end; 9 ????}10 ????function rewind(){ 11 ????????$this->cur = $this->start;12 ????}13 ????function key(){14 ????????return $this->cur;15 ????}16 ????function current(){17 ????????return pow( $this->cur, 2 );18 ????}19 ????function next(){20 ????????$this->cur++;21 ????}22 ????function valid(){23 ????????return $this->cur <= $this->end;24 ????}25 } ???26 27 $obj = new NumberSquared( 3, 9 );28 foreach( $obj as $key => $value ){29 ????print "the square of $key is $value" . PHP_EOL;30 }类本身一般用来表示数据和拥有与这些数据的交互方法，所以一般不需要一个纯粹的类迭代器，我们可以实现另一个接口：IteratorAggregate，接口摘要如下：
IteratorAggregate extends Traversable {/* Methods */abstract public Traversable getIterator ( void )}这个接口只有一个方法，作用是创建一个外部的迭代器接口
改造后的迭代，实现了迭代器与数据处理的分离：
1 class NumberSquared implements IteratorAggregate { 2 ????private $start; 3 ????private $end; 4 ?5 ????function __construct( $start, $end ) { 6 ????????$this->start = $start; 7 ????????$this->end = $end; 8 ????} 9 10 ????function getIterator(){11 ????????return new NumberSquaredIterator( $this );12 ????} ???13 14 ????function getStart(){15 ????????return $this->start;16 ????}17 18 ????function getEnd(){ 19 ????????return $this->end;20 ????}21 }22 23 class NumberSquaredIterator implements Iterator {24 ????private $cur;25 ????private $obj;26 ????function __construct( $obj ) {27 ????????$this->obj = $obj;28 ????}29 ????function rewind(){ 30 ????????$this->cur = $this->obj->getStart();31 ????}32 ????function key(){33 ????????return $this->cur;34 ????}35 ????function next(){36 ????????$this->cur++;37 ????}38 ????function current(){39 ????????return pow( $this->cur, 2 );40 ????}41 ????function valid(){42 ????????return $this->cur <= $this->obj->getEnd();43 ????}44 }45 46 $obj = new NumberSquared( 3, 9 );47 foreach( $obj as $key => $value ) {48 ????print "the $key is $value " . PHP_EOL;49 }php面向对象高级-魔术方法与迭代器
原文地址：https://www.cnblogs.com/ghostwu/p/8459604.html