PHP OOP classes of store pattern

Question

I have a doubt about the design of a system to manage items of a store using OOP. I created the abstract class Product that will have the attributes $name and $price. Later I created the class Smartphone that extends Product. Smartphone has the attributes $brand and $os. Later I created the class Computer that extends Product and has attributes $cpuFrequency and $ram. Now, if I want to create an object corresponding to the Nexus 5, for example, what i have to do? Consider, for example, that this object will have

$name = "Nexus 5"
$price = "250"
$brand = "LG"
$os="Android"
$cpuFrequency "2.0"
$ram = "2".

Here an example of classes.

abstract class Product {
    private $name;
    private $price; 
    //more methods
}

class Smartphone extends Product{
    private $brand;
    private $os;    
}

class Computer extends Product {
    private $cpuFrequency;
    private $ram;   
}

Also considered that there may be Computer without $os and Smartphone without $ram. just one example: D

P.S. I know that smartphone is a computer. I did a bad example. Please think at Telephone and Computer. Telephone has $number and $operator. Now i want to create a Smartphone that is at the same time Telephone and Computer.

Thanks for all and sorry again for my english

Answer 1

Normally, you should write constructors to your classes in some way that "child" class initialize the super class, to keep everything consistent.

abstract class Product {
    private $name;
    private $price; 
    //more methods

    public __construct($name, $price){
        $this->name = $name;
        $this->price =$price;
    }
}

class Smartphone extends Product{
    private $brand;
    private $os;
    // default value to $os: like that, we can create a Smartphone whitout an os
    public __construct($name, $price, $brand, $os = null){
        parent::__construct($name, $price);
        $this->brand = $brand;
        $this->os =$os;
    }
}

class Computer extends Product {
    private $cpuFrequency;
    private $ram;
    // default value to $ram: with this, we can create a Computer whiout ram
    public __construct($name, $price, $frequency, $ram = null){
        parent::__construct($name, $price);
        $this->frequency = $frequency;
        $this->ram =$ram;
    }

}

Then, to create a Computer, you can do, for

$computer = new Computer('notBuiltToWindows', 560 , 2.0, 4);

or, to create the Nexus in your example:

$nexus = new Smartphone($name, $price, $frequency, $ram);

and, to create a smartphone whitout a ram

$nexus = new Smartphone($name, $price, $frequency);

Answer 2

You could try using a ProductProperties class like so:

class ProductProperties
{
    private properties = array();

    public function getProperties()
    {
        return this->properties;
    }

    public function addProperty($id, $value)
    {
        this->properties[$id] = $value;
    }

    public function getProperty($id)
    {
        return this->properties[$id];
    }
}

abstract class Product
{
    private $properties;
    //more methods

    public function __construct(ProductProperties $properties)
    {
        $this->properties = $properties;
    }
}

You could pass an object of class ProductProperties to any of your product and let it handle all properties related issues. This would make for a more flexible design, this way you don't need to subclass just because a product has a different set of properties. Remember subclassing is all about changing or adding behavior.