Strategy pattern in PHP.

strategy.php

<?php
//strategy
interface Average
{
    public function calculate(Values $values);
}

//concrete strategy
class AveragePondered implements Average
{
	public function calculate(Values $values)
	{
        	$value =  $values->getValues();
        	$weight = $values->getWeight();
        	$multiplicationResult = 0;
        	$weightSumResult = array_sum($weight);
        	for($i = 0; $i < count($value) && $i < count($weight); $i++)
		{
			$multiplicationResult += $value[$i] * $weight[$i];
		}
        	return $average = $multiplicationResult / $weightSumResult;
	}
}

//concrete strategy
class AverageArithmetic implements Average
{
	public function calculate(Values $values)
	{
        	$elements = $values->getValues();
        	$elementsSum = array_sum($elements);
        	$totalElements = count($elements);
        	return $average = $elementsSum / $totalElements;
	}
}

//context
abstract class Values
{
	protected $value;
	protected $average;
	
	protected function __construct(Average $average)
	{
	    $this->average = $average;
	}

   	public function addValues($value)
   	{
		$this->value[] = $value; 
    	}
    	public function getValues()
    	{
        	return $this->value;
    	}
    	abstract public function getAverage();
}

class Pondered extends Values
{
	private $weight; 
	
	public function __construct(Average $average)
	{
		parent::__construct($average);
	}

	public function addWeight($weight)
	{
		$this->weight[] = $weight; 
	}

	public function getWeight()
    	{
    		return $this->weight;
    	}

    	public function getAverage()
    	{
    		return $this->average->calculate($this);
    	}
}

class Arithmetic extends Values
{
	public function __construct(Average $average)
	{
		parent::__construct($average);
		
	}
    	public function getAverage()
    	{
        	return $this->average->calculate($this);
    	}
}

//execution
$valuePondered = new Pondered(new AveragePondered());
$valuePondered->addValues(5);
$valuePondered->addWeight(2.2);
$valuePondered->addValues(8);
$valuePondered->addWeight(3.3);
$valuePondered->addValues(5);
$valuePondered->addWeight(4.4);
$valuePondered->addValues(4);
$valuePondered->addWeight(5.5);
var_dump("Pondered " .$valuePondered->getAverage());


$valueArithmetic = new Arithmetic(new AverageArithmetic());
$valueArithmetic->addValues(10);
$valueArithmetic->addValues(10);
$valueArithmetic->addValues(10);
$valueArithmetic->addValues(10);
var_dump("Arithmetic " .$valueArithmetic->getAverage());