PHP: OOP constructors signatures - oop

Question

I've class called Books
class Books {
/* Member variables */
var $price;
var $title;
function __construct( $title, $price ) {
$this->title = $title;
$this->price = $price;
}
/* Member functions */
function getPrice(){
echo $this->price ."<br/>";
}
function getTitle(){
echo $this->title ." <br/>";
}
}
then I've added another class which inherit my Book class something like this
class Novel extends Books {
var $publisher;
function getPublisher(){
echo $this->publisher. "<br />";
}
function __construct( $publisher ) {
$this->publisher = $publisher;
}
}
Now I want to invoke Novel class and set all of its properties such as title, price and publisher via constructor so if I do this
$physics = new Books("Physics for High School",1);
$testNovel = new Novel("Test Publisher");
it works great it set the publisher value of my $testNovel object
so how can I set value of Title and price while creating object of it??
even If I try
$testNovel = new Novel("Test Title",4,"Test Pubisher");
here "Test Title" is set as publisher instead of "Test Publisher". Moreover, if I put more values inside signature something like this
$testNovel = new Novel("Test Title",4,"New Pub","","Whatever","","Why it allow");
it does not throw any error why??

Answer 1

When you extend a class that defines a constructor, with a class that defines it's own constructor, you need to call the parent constructor yourself supplying the required parameters. E.g.:
class Novel extends Books
{
// ...
function __construct($title, $price, $publisher)
{
$this->publisher = $publisher;
parent::__construct($title, $price);
}
}
From the manual:
Note: Parent constructors are not called implicitly if the child class
defines a constructor. In order to run a parent constructor, a call to
parent::__construct() within the child constructor is required. If the
child does not define a constructor then it may be inherited from the
parent class just like a normal class method (if it was not declared
as private).