question about inheritence...

[Monkee_Of_Evil]

I've moved into writing classes and using polymorphism in my code. I've written a generic Database class that does various things such as running queries, switching databases, generating arrays of search results, as well as some other misc. functions I find myself using in pretty much every php program I wrote.

As it is right now I just create an instance of the database class within each of my classes that I want to use the database.

What I want to do is have my other classes inherit from database. I know i have to use the keyword extends ( like in java ).

My questions are this:

• Is the database constructor automatically called?
• Can I do something like super->runQuery() to use functions from the parent class?

[Kudose]

Personally, I call my connection object after I have the the parameters, so I dont have to change my contructor every site I build. I just include a file that sets the variables and then calls $dbclass->connect().

i.e.

$db = new DB;
$db->user = 'travis';
$db->loc = 'localhost';
$db->pass = 'abc';
$db->name = 'mydb';

$db->connect();

And yes, you can call methods from the parent class from the child. It inherits all parent methods, unless they are private (I think on the private part).

That may not have helped you at all, but that's what I do ... 🙂

[Monkee_Of_Evil]

Kudose wrote:

Personally, I call my connection object after I have the the parameters, so I dont have to change my contructor every site I build. I just include a file that sets the variables and then calls $dbclass->connect().

i.e.

$db = new DB;
$db->user = 'travis';
$db->loc = 'localhost';
$db->pass = 'abc';
$db->name = 'mydb';

$db->connect();

And yes, you can call methods from the parent class from the child. It inherits all parent methods, unless they are private (I think on the private part).

That may not have helped you at all, but that's what I do ... 🙂

I guess what I should be asking is this..

In java, if you want to explicitly call a function from the parent class you use this:

super.dbConnect();

and if i want to initialize the parent constructor i would do super( params );

I want to know if this is available in php in some form or another.

[Shrike]

You use 'super' in Java to call methods which have been overridden in a derived class. In PHP you can use 'parent' to refer to methods which have been overridden. In both PHP and Java any methods which are defined in a parent class but not the derived one are automatically available in the derived one (unless they are marked as private in Java and PHP 5). In Java you may or may not need to reference the current context with 'this', in PHP you must use the token '$this'.

Going back to your original question, inheritance should be used to refine a class, not simply to provide it with certain functionality. If a class needs a database object pass it as a parameter. Inheritance should be used as sparingly as possible, composition is a much more favourable approach as it leads to more modular development.