What do braces surrounding a member variable mean in PHP?
<p>I am wondering what { } in the following. What { } is doing here? $this->{$key} = $value;</p>

<p>Thanks in advance.  </p>

<p>In one file </p>

<pre><code>$config['field']['calendar'] = array('type'=&gt;'boolean');
$config['field']['category'] = array('type'=&gt;'boolean');
$config['field']['customers'] = array('type'=&gt;'boolean');  
...
$this-&gt;preference_form-&gt;initalize($config);
</code></pre>

<p>And in Preference_form.php</p>

<pre><code>function initalize($config = array())
{
    foreach($config as $key =&gt; $value)
    {
        $this-&gt;{$key} = $value;
    }
}
</code></pre>
