Call extend class.

[eluser]Sumon[/eluser]
have a try

Code:

class Newcontent extends Content {
    
        function __construct() {
            $this->SetInitialValues();
        }
        
        function getDate() {
         return $this->modified_date;
        }
        
}
$x = new Newcontent();
print_r($x->getDate());

Content class __construct() not called anywhere. so that explicit call of SetInitialValues() resolve the issue.
may be helpful for you