PHP: Can't access a function from a constructor?

[wige]

Hey everyone. I am in the process of writing a PHP class that will parse RSS files. However, in the class constructor, I can't seem to get the filter_vars() function to work. Any suggestions (or see anything I messed up)?

// Create the feed using the passed url
    public function __construct ($in_url) {
        if (filter_var($in_url, FILTER_VALIDATE_URL)) {
            $this->feed = $in_url;
            if ($xml = simplexml_load_file($in_url)) {
                $this->readFeed($xml);
            } else {
                $this->status = 'Unable to open file <a href="$in_url">$in_url</a>';
            }
        } else {
            $this->status = 'Invalid URL';
        }
    } 

The error I get is "PHP Fatal error: Call to undefined function filter_var() in /www/rss_feed.php on line 59"

I know the filter_var method is supported, since I have an identical line in another class I have written.

[wige]

Never mind, I found my screwup.

[kgun]

Good that you found the error.

1. I think you already know this debugging function: PHP: var_dump - Manual that
   
2. But do you know the PHP: Reflection - Manual API that follows with php 5? That opens for much more advanced debugging.

See APRESS.COM : PHP 5 Objects, Patterns, and Practice : 9781590593806 chapter 5

"Object Tools"

for a good explanation.