Example of Strategy Pattern in PHP
A guide on the Strategy Pattern in PHP with a concrete example, explaining how to implement and use this design pattern in object-oriented programming.
The Strategy pattern allows changing the algorithm or strategy at runtime without modifying the class that is using the strategy. It is useful for creating flexible and maintainable behavior in your code.
<?php
// Strategy Pattern in PHP
// Strategy Interface defining the common method
interface PaymentStrategy {
public function pay($amount);
}
// Concrete classes for different payment strategies
class CreditCardPayment implements PaymentStrategy {
public function pay($amount) {
echo "Paid $amount using Credit Card.\n";
}
}
class PayPalPayment implements PaymentStrategy {
public function pay($amount) {
echo "Paid $amount via PayPal.\n";
}
}
class CashPayment implements PaymentStrategy {
public function pay($amount) {
echo "Paid $amount in cash.\n";
}
}
// ShoppingCart class uses the strategy for payment
class ShoppingCart {
private $paymentStrategy;
// Set the payment strategy
public function setPaymentStrategy(PaymentStrategy $strategy) {
$this->paymentStrategy = $strategy;
}
// Perform the payment
public function checkout($amount) {
$this->paymentStrategy->pay($amount);
}
}
// Using Strategy Pattern
$cart = new ShoppingCart();
// Pay with credit card
$cart->setPaymentStrategy(new CreditCardPayment());
$cart->checkout(100); // Output: Paid 100 using Credit Card.
// Pay with PayPal
$cart->setPaymentStrategy(new PayPalPayment());
$cart->checkout(200); // Output: Paid 200 via PayPal.
// Pay with cash
$cart->setPaymentStrategy(new CashPayment());
$cart->checkout(300); // Output: Paid 300 in cash.
?>Detailed explanation:
-
interface PaymentStrategy: This is the common strategy interface for different payment methods, containing thepay($amount)method. -
CreditCardPayment,PayPalPayment,CashPayment: These concrete classes implement thePaymentStrategyinterface, each representing a different payment method. -
ShoppingCart: This class handles payment, allowing different strategies to be applied throughsetPaymentStrategy, and executing payments usingcheckout. -
Using Strategy Pattern: The
ShoppingCartobject can dynamically switch between different payment strategies (CreditCardPayment,PayPalPayment,CashPayment) without altering the core logic inShoppingCart.
PHP Version:
This code is compatible with PHP 5.0 and above.