Can I extend the constructor of the sueprtype? documentation doesnt say anything about extending functions.
I want to create a class which connects to a database when the subtypes are initialized but I don't want to write a connection code for each subtype. So I'd like to do it in the constructor of the supertype but I also want subtypes to have constructors.
Methods don't get "extended" per se; classes get extended. The methods of those classes still exist, and can be invoked if they are scoped appropriately.
To more directly answer your question, you can call parent::__construct() to invoke the __construct() method of a superclass. See the PHP documentation on constructors and destructors for more information.
From php.net
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.
http://www.php.net/manual/en/language.oop5.decon.php
So what you do is connect to the database in the superclass constructor. Then create your subclass constructor and call parent::__construct()
But, it would probably be better to explicitly connect. In the base class call $this->connect(), which would be defined in the parent class.
Just as you can use parent::methodName() to call the parents version of a function, so you can call self::methodName() to call the current classes implementation of a method.
This links may help u
Yes, you can override the constructor just like any other method in a class:
<?php
class DbSuper {
function __construct() {
echo "db connection using super class<br/>";
}
}
class DbSub extends DbSuper {
function __construct() {
echo "db connection using sub class<br/>";
}
}
class DbSubNoConstr extends DbSuper {
}
class DbSubBothConstr extends DbSuper {
function __construct() {
echo "execute subclass code<br/>";
parent::__construct();
}
}
new DbSub(); //prints db connection using sub class
new DbSubNoConstr(); // prints db connection using super class
new DbSubBothConstr(); // prints execute subclass code db connection using super class
?>
