Php: Check if a variable is an object
<p>Every time I get a variable through $_GET I want to verify that it is indeed an object of the User class.</p>

<p>So:</p>

<pre><code>if (isUser($_GET['valid_user']))
{
...
}
</code></pre>

<p>is there a built in function to use instead of this so called "isUser"?</p>

<p>Thanks a lot!</p>
