PHP防止创建未在类中定义的属性

Question

<?php
//Simple object to keep track of an Article
class ArchiveArticle
{
    public $timestamp;
    public $filename;
    public $slug;
    public $category;
    public $status;
    public $pubdate;
    public $ranking;
    public $newsgate_state;
    public $newsgate_story_id;
    public $newsgate_budget_id;
    public $newsgate_text_id;
    public $newsgate_profile;
    public $taxonomy;
    public $overline;
    public $net_title;
    public $headline;
    public $teasertitle;
    public $teasersummary;
    public $subhead;
    public $summary;
    public $byline_name;
    public $dateline;
    public $paragraphs = array();
    public $more_infos = array();
    public $shirttail;
    public $images = array();
}

$obj = new ArchiveArticle();
$obj->foo = 'bar'; //How can I stop this?
?>

Answer 1

To your class add:

public function __get($name) { return NULL; }

public function __set($name, $value) { }

Explanation: those two methods will intercept any access to a non-existant and/or protected/private property, also preventing its creation if it does not exists.

See also http://php.net/manual/en/language.oop5.magic.php

As per @DCoder suggestion, you could also do:

public function __get($name) {
  throw new Exception("Property $name cannot be read");
}

public function __set($name, $value) {
  throw new Exception("Property $name cannot be set");
}