5_example scenario of abstract pattern

 For creating better understanding, let implement the abstract design pattern the way it fit in real scenario.
There ia a company on large scale build cars in large numbers. They build different types of cars.
Petrol, Electric, Hybrid.

But there was a big problem

Problem: Wrong Parts, Wrong Car
Car builder mixes the parts in cars,
Put petrol engine in electric car and Electric tyres in Petrol car.
In result the car explosion, customers got angry and choas!

Than Leadership of the company summoned the best engineers to fix this problem.
He said we need a system where,

1. Right part fit in the right car.
2. Builder no need to know the making of the parts they just build the car.
3. We can add new car easily in future.

So Engineers decide to have a Abstract Factory Design pattern.

Abstract Factory

Engineer Build the abstract factory(Main Factory) that is blueprint(Interface). This will decide what will be build in the factory.

<?php

interface CarFactory {

    public function createEngine(): Engine;

    public function createTyre(): Tyre;

}

?>

This insure that every factory to be build these two things.
1. Engine
2. Tyre

Now Production factory is divided into multiple factories and each factory will responsible for development of only specific type of engine (Electric, petrol, Hybrid etc).

ElectricCarFactory

This factory will only develop Electric Engine.

<?php

class ElectricCarFactory implements CarFactory {

    public function createEngine(): Engine {

        return new ElectricEngine();  // ⚡

    }

    public function createTyre(): Tyre {

        return new ElectricTyre();  // low-resistance tyres

    }

}

?>

PetrolCarFactory

This factory will only develop Petrol Engine. 

<?php

class PetrolCarFactory implements CarFactory {

    public function createEngine(): Engine {

        return new PetrolEngine();  // V8 or V6

    }

    public function createTyre(): Tyre {

        return new PetrolTyre();  // standard road tyres

    }

}

?>

Car Work Shop (Client Code)

This is the assembly line where decide which factory is selected. Now builder are not in worry about the mixing of the parts.

<?php

function buildCar(CarFactory $factory) {

    $engine = $factory->createEngine();

    $tyre = $factory->createTyre();

    echo $engine->getType();

    echo $tyre->getType();

}

?>

Now Choose the factory, desire car will automatically will be build.

<?php

buildCar(new ElectricCarFactory());  // Builds only electric car parts

buildCar(new PetrolCarFactory());   // Builds only petrol car parts

?>

Achievements

1. Factories made the right product
2. Now builder not worry about the mixing of the parts.
3. that is important we can Develop new type of car (hybrid). We can add/create new factory.

Real world Application Example

1. Integration Payment Gateways

Integrating new Payment gateway alongside with existing payment gateway for customer to have multiple option of making online payment.

Support your system work with stripe, Now you want to add new payment gateway Paypal.
You will choose to abstract design pattern you that client have option to preceed with one payment method at a time.

<?php

interface PaymentGateway {

    public function pay($amount);

}

class PayPalAdapter implements PaymentGateway {

    private $paypal;

    public function __construct(PayPalAPI $paypal) {

        $this->paypal = $paypal;

    }

    public function pay($amount) {

        $this->paypal->makePayment($amount);

    }

}

?>

2. Connecting legacy system with new system
Let say you have old logging system and it have its implementation of logging.

<?php

class LegacyLogger {

    public function writeLog($msg) { ... }

}

?>

But your new app expects.

<?php

interface Logger {

    public function log($message);

}

?>

You can you Abstract factory design pattern to reuse the old class without changing.

3. Laravel Socialite Login System
System have the ability to login either though Google Api, Facebook Api, Github Api.
Using Specific Api to login on user login preference.

<?php

Socialite::driver('google')->user();

?>