php 5 constructor _construct does not work

Question

We have php 5.3.0 and I would like to use the constructor _construct. But somehow this constructor is not called when an instance of the class is made. And old constructor ( function ClassName() ) on the other hand works. Should not the new version (_construct) work with php 5.3.0 ?

Another thing I would like to build an constructor with arguments. But the parent constructor has none. If I try to build this php tells me the constructor has to have the same construct like the parent constructor. Is this so ?

Example:

abstract class Foo{

   function _construct(){
   }
}

class Bar extends Foo{

   function _construct($arg){
     parent::_construct();
   } 
}

Thanks for replies

Answer 1

__construct() (two underscores)

Second question: fix the underscores in __construct() and see if this is still a problem.