Question

我有以下数组：

$allZones = array (
    'header'    =>  array('div1', 'div2'),
    'content'   =>  array('div3', 'div4')        
);

我正在使用它以下列方式创建实例：

foreach($allZones as $newZoneId => $newZoneSubs) {
    $newZone = new zone($newZoneId, $newZoneSubs);
}

'zone'类的构造函数如下所示：

public function __construct($newZoneId, array $newZoneSubs) {
    $this->zoneId = $newZoneId;

    if(is_array($newZoneSubs)) {
        foreach($newZoneSubs as $newZoneSub) {
                $this->zoneSubs[] = new zone($newZoneSub, '');
        }
    }
    else {
        echo "1: " . $newZoneSubs;
    }
}

由于某种原因，$ newZoneSubs为空。

谁能告诉我为什么？

Answer 1

new zone($newZoneSub, '') - 你在这里传递一个字符串，但是第二个参数必须是一个数组，否则你会因为参数提示__construct($newZoneId, array $newZoneSubs)而得到一个可捕获的致命错误

尝试

foreach($newZoneSubs as $newZoneSub) {
    $this->zoneSubs[] = new zone($newZoneSub, array());
}

e.g。

<?php
$allZones = array (
    'header'    =>  array('div1', 'div2'),
    'content'   =>  array('div3', 'div4')        
);
foreach($allZones as $newZoneId => $newZoneSubs) {
    $newZone = new zone($newZoneId, $newZoneSubs);
    echo $newZone, "\n";
}

class zone {
    protected $zoneId, $zoneSubs;

    public function __construct($newZoneId, array $newZoneSubs) {
    $this->zoneId = $newZoneId;
    $this->zoneSubs = array();
    foreach($newZoneSubs as $newZoneSub) {
            $this->zoneSubs[] = new zone($newZoneSub, array());
        }
    }

    public function __toString() {
        return $this->foo(0);
    }

    protected function foo($n) {
        $rv =  str_repeat(' ', $n)
        .'zoneid='
        .$this->zoneId
        ."\n";
        foreach( $this->zoneSubs as $sub ) {
            $rv .= $sub->foo($n+1);
        }
        return $rv;
    }
}

打印

zoneid=header
 zoneid=div1
 zoneid=div2

zoneid=content
 zoneid=div3
 zoneid=div4

Answer 2

问题出在你的构造函数中;如果$newZoneSubs是可选的，您可以这样定义：

public function __construct($newZoneId, array $newZoneSubs = array()) 
{
    $this->zoneId = $newZoneId;

    foreach($newZoneSubs as $newZoneSub) {
        $this->zoneSubs[] = new zone($newZoneSub);
        //                                      ^^
        //                                   not passing the second param
    }
}

将数组传递给__construct

2 个答案: