Strategy Pattern

In Strategy pattern, a class behavior or its algorithm can be changed at run time. This type of design pattern comes under behavior pattern.

Code Example

<?php

class Context
{
    private $strategy;

    public function __construct(Strategy $strategy)
    {
        $this->strategy = $strategy;
    }
    
    public function setStrategy(Strategy $strategy)
    {
        $this->strategy = $strategy;
    }
    
    public function doSomeBusinessLogic(): void
    {
        echo "Context: Sorting data using the strategy (not sure how it'll do it)\n";
        $result = $this->strategy->doAlgorithm(["a", "b", "c", "d", "e"]);
        echo implode(",", $result) . "\n";
    }
}

interface Strategy
{
    public function doAlgorithm(array $data): array;
}

class ConcreteStrategyA implements Strategy
{
    public function doAlgorithm(array $data): array
    {
        sort($data);

        return $data;
    }
}

class ConcreteStrategyB implements Strategy
{
    public function doAlgorithm(array $data): array
    {
        rsort($data);

        return $data;
    }
}

$context = new Context(new ConcreteStrategyA);
echo "Client: Strategy is set to normal sorting.\n";
$context->doSomeBusinessLogic();

echo "\n";

echo "Client: Strategy is set to reverse sorting.\n";
$context->setStrategy(new ConcreteStrategyB);
$context->doSomeBusinessLogic();