PHP - Classes inheritance and combining with another class - php

Question

I want to write something inheriting classes in the structure of the 3 levels. Abstract example of such.
couriers_list -> courier -> courier_name
class couriers_list {
// I'm searches courier_name of the database and reference to the class of courier_name found in database
public function show_courier() {
return $this->xxx();
}
}
class courier extends couriers_list {
// Function for the courier
// Probably it would interface or abstraction
}
class courier_name extends courier {
// Methods of accurately courier eg. Calculation associated with the delivery
// Here each courier would separate file php eg. ups.php
public function xxx() {
return 'xxx';
}
}
$k = new couriers_list();
echo $k->xxx();
I don't think I can extends courier to courier_list, because I don't have access to methods descendants. From the outside, I would like to refer only to the class couriers_list, and she has to take the info from the database and take methods resulting from courier_name.
How to put this problem to organize object?

Answer 1

Your class Courrier should be an interface since it used to define the way your Courrier should be used
interface CourrierInterface
{
const CLASS_NAME = __CLASS__;
public function getName();
public function getPrices();
public function XXX();
public function calculateDelivery($from, $to);
/** these are just example add here all the method that define a courier */
}
Then for each courrier you have, you should implements de CourrierInterface
class UpsCourrier implements CourrierInterface
{
private $name;
public function getName()
{
return $this->name;
}
public function setName($name)
{
$this->name = $name;
}
public function XXX()
{
// do something
}
}
I don't think the CourrierList should know about the database but just need to contains all the courrier object you have.
Here i used the project
https://github.com/yvoyer/collection
in order to manage the collection (TypedCollection class), it allows to control the type of class you want in your collection (here courrierInterface), but you can use an array if you want it much simple.
I create two XXX method, one for a specific courrier (since its a list) and another for apply to all the list. I don't know your need so take what you need
class CourrierList
{
/**
* TypedCollection
*/
private $courrierList;
public function __construct()
{
// i prefer to use a collection class that valid my type instead of an array, your choice!
$this->courrierList = new TypedCollection("CourrierInterface");
}
public function addCourrier(CourrierInterface $courrier)
{
$this->courrierList->add($courrier);
}
public function removeCourrier(CourrierInterface $courrier)
{
$this->courrierList->removeElement($courrier);
}
protected function getCourrierByName($courrierName)
{
$closure = function (CourrierInterface $courrier) use ($courrierName) {
return $courrier->getName() == $courrierName;
};
return $this->courrierList->filter($closure)->toArray();
}
// since its a list, you must be able to select your courrier to execute the XXX() method
public function XXXByName($name)
{
$courrier = $this->getCourrierByName($name);
$courrier->XXX();
}
// if you prefer to apply to all your courrierList just do
public function XXX()
{
foreach ($this->courrierList as $courrier) {
$courrier->XXX();
}
}
}
Since i don't think the CourrierList should know about the database, you can create a factory that does fetch the data in your db and create all the courriers. Here dbConnection is your choice, pdo etc... i just made an example, find the good way to make query.
class CourrierListFactory
{
private $dbConnection;
public function __construct(DbConnection $connection)
{
$this->dbConnection = $connection;
}
public function createCourrierList()
{
$results = $this->dbConnection->query(".....")->getResults();
$courrierList = new CourrierList();
foreach ($results as $result) {
$courrier = null;
switch ($result['name']) {
case 'ups':
$courrier = new UpsCourrier();
break;
case 'fedex':
$courrier = new FedexCourrier();
break;
/** and so on ... */
default:
// maybe throw exception if courier is not handle
}
$courrier->setName("....");
/** prepare your object here */
// add the courrier to the list
$courrierList->addCourrier($courrier);
}
return $courrierList;
}
}
Finally its how you use all of this, first create a dbCOnnection, then build your list, then you can acces
$dbConnection = new DbConnection();
// the factory allows you to separate the database from the List class and may be to generate
// your list in an other way later (using apis, etc...)
$factory = new CourrierListFactory($dbConnection);
$courrierList = $factory->createCourrierList();
$courrierList->XXX(); // apply to all
$courrierList->XXXByName("ups"); // apply just to ups courrier