Let's do something a little more interesting. OOP is fantastic when creating an 'API' (application programming interface) which will allow other developers to perform certain functionality.

I use at least these methods:

'Create' - this creates a new 'item' and saves it in the database.

'Load' - this loads an item ready for use.

'Update' - this updates the item in the database.

'Delete' - this deletes an item from the database.

So, a base API class would look like:


<?php
class API {

    /**
    * This class variable is set by SetupDB
    */
    var $DBConnection = null;

    /**
    * In the base class, the constructor doesn't do anything.
    */
    function __construct() {
    }

    /**
    * In the base class, the constructor doesn't do anything.
    * This is called by PHP4.
    */
    function API() {
        $this->__construct();
    }

    /**
    * This will set up DBConnection ready for use.
    */
    function SetupDB() {
        if (is_null($this->DBConnection)) {
            $connection_string = 'dbname=test';
            $connection = pg_connect($connection_string);
            $this->DBConnection = $connection;
        }
    }

    /**
    * This is overridden by the child class(es).
    */
    function Create() {
        echo "Can't call 'create' on the base API class<br/>";
        return false;
    }

    /**
    * This is overridden by the child class(es).
    */
    function Load() {
        echo "Can't call 'load' on the base API class<br/>";
        return false;
    }

    /**
    * This is overridden by the child class(es).
    */
    function Update() {
        echo "Can't call 'update' on the base API class<br/>";
        return false;
    }

    /**
    * This is overridden by the child class(es).
    */
    function Delete() {
        echo "Can't call 'delete' on the base API class<br/>";
        return false;
    }

    /**
    * This gets a class variable after making sure it is available.
    * If it's not a set class variable (ie it doesn't exist), then this will return false.
    */
    function Get($getname='') {
        if (!isset($this->$getname)) {
            return false;
        }
        return $this->$getname;
    }

    /**
    * This sets a class variable after making sure it is available.
    * If it's not a set class variable (ie it doesn't exist), then this will return false.
    * Otherwise the variable is set and this will return true.
    */
    function Set($setname='', $value='') {
        if (!isset($this->$setname)) {
            return false;
        }
        $this->$setname = $value;
        return true;
    }
}

?>