gistfile1.txt

// Singleton Class
class SumSingleton
{
    private static $instance;
    private $result;

    private function __construct() {}

    public static function getInstance()
    {
        if (!self::$instance) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    public function sumArray($arr)
    {
        $this->result = array_sum($arr);
    }

    public function getResult()
    {
        return $this->result;
    }
}

// Strategy Interface
interface SumStrategy
{
    public function sumArray($arr);
}

// Concrete Strategy - Using array_sum
class ArraySumStrategy implements SumStrategy
{
    public function sumArray($arr)
    {
        return array_sum($arr);
    }
}

// Concrete Strategy - Using loop
class LoopSumStrategy implements SumStrategy
{
    public function sumArray($arr)
    {
        $sum = 0;
        foreach ($arr as $num) {
            $sum += $num;
        }
        return $sum;
    }
}

// Context (Context acts as a strategy manager)
class SumContext
{
    private $strategy;

    public function setStrategy(SumStrategy $strategy)
    {
        $this->strategy = $strategy;
    }

    public function sumArray($arr)
    {
        return $this->strategy->sumArray($arr);
    }
}

// Decorator to add sum functionality
class SumDecorator
{
    protected $arraySum;

    public function __construct(ArraySum $arraySum)
    {
        $this->arraySum = $arraySum;
    }

    public function sum()
    {
        return $this->arraySum->sum();
    }
}

// Usage
$a = [1, 2, 3];

// Singleton
$sumSingleton = SumSingleton::getInstance();
$sumSingleton->sumArray($a);
$sumResultSingleton = $sumSingleton->getResult();

// Strategy - array_sum
$sumContext = new SumContext();
$sumContext->setStrategy(new ArraySumStrategy());
$sumResultStrategyArraySum = $sumContext->sumArray($a);

// Strategy - loop
$sumContext->setStrategy(new LoopSumStrategy());
$sumResultStrategyLoop = $sumContext->sumArray($a);

// Decorator
$arraySum = new ArraySum($a);
$sumDecorator = new SumDecorator($arraySum);
$sumResultDecorator = $sumDecorator->sum();

echo "Sum using Singleton: " . $sumResultSingleton . "\n";
echo "Sum using Strategy (array_sum): " . $sumResultStrategyArraySum . "\n";
echo "Sum using Strategy (loop): " . $sumResultStrategyLoop . "\n";
echo "Sum using Decorator: " . $sumResultDecorator . "\n";