In Laravel, an abstract class is a base class that cannot be instantiated but can define methods and properties that child classes must implement. Abstract classes are commonly used to enforce a common structure or behavior across multiple related classes.

Here are five real-world scenarios demonstrating abstract classes in Laravel from different domains:

1. E-Commerce Domain: Payment Processing

Abstract class for payment gateways ensuring all payment gateway implementations follow a standard interface.

abstract class PaymentGateway
{
    protected $amount;

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

    abstract public function processPayment();
    abstract public function refund();
}

Child classes:

class PayPalGateway extends PaymentGateway
{
    public function processPayment()
    {
        return "Processing payment of {$this->amount} via PayPal.";
    }

    public function refund()
    {
        return "Refunding payment via PayPal.";
    }
}

class StripeGateway extends PaymentGateway
{
    public function processPayment()
    {
        return "Processing payment of {$this->amount} via Stripe.";
    }

    public function refund()
    {
        return "Refunding payment via Stripe.";
    }
}

2. Education Domain: Notification System

Abstract class for sending notifications through various channels (e.g., SMS, Email).

abstract class Notification
{
    protected $recipient;

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

    abstract public function send();
}

Child classes:

class EmailNotification extends Notification
{
    public function send()
    {
        return "Sending email to {$this->recipient}.";
    }
}

class SmsNotification extends Notification
{
    public function send()
    {
        return "Sending SMS to {$this->recipient}.";
    }
}

3. Logistics Domain: Delivery System

Abstract class for managing deliveries, enforcing common methods for different delivery providers.

abstract class DeliveryService
{
    protected $package;

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

    abstract public function calculateDeliveryTime();
    abstract public function trackPackage();
}

Child classes:

class FedExDelivery extends DeliveryService
{
    public function calculateDeliveryTime()
    {
        return "Delivery time for {$this->package} via FedEx is 3 days.";
    }

    public function trackPackage()
    {
        return "Tracking {$this->package} with FedEx.";
    }
}

class UPSDelivery extends DeliveryService
{
    public function calculateDeliveryTime()
    {
        return "Delivery time for {$this->package} via UPS is 5 days.";
    }

    public function trackPackage()
    {
        return "Tracking {$this->package} with UPS.";
    }
}

4. Healthcare Domain: Medical Record Management

Abstract class for managing patient records in different hospital departments.

abstract class PatientRecord
{
    protected $patientId;

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

    abstract public function fetchDetails();
    abstract public function updateRecord();
}

Child classes:

class CardiologyRecord extends PatientRecord
{
    public function fetchDetails()
    {
        return "Fetching cardiology records for patient {$this->patientId}.";
    }

    public function updateRecord()
    {
        return "Updating cardiology records for patient {$this->patientId}.";
    }
}

class NeurologyRecord extends PatientRecord
{
    public function fetchDetails()
    {
        return "Fetching neurology records for patient {$this->patientId}.";
    }

    public function updateRecord()
    {
        return "Updating neurology records for patient {$this->patientId}.";
    }
}

5. Finance Domain: Tax Calculation

Abstract class for tax calculation ensuring common logic for different regions or countries.

abstract class TaxCalculator
{
    protected $income;

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

    abstract public function calculateTax();
}

Child classes:

class USATaxCalculator extends TaxCalculator
{
    public function calculateTax()
    {
        return "Calculating tax for {$this->income} in the USA.";
    }
}

class CanadaTaxCalculator extends TaxCalculator
{
    public function calculateTax()
    {
        return "Calculating tax for {$this->income} in Canada.";
    }
}

Key Points:

Abstract classes cannot be instantiated directly.
They are useful for enforcing consistent behavior across related classes.
They can contain both abstract methods (without implementation) and concrete methods (with implementation).
Use Laravel's Service Providers to bind implementations to interfaces or abstract classes in the container for dependency injection.

Inheritance and Abstract Classes