1.2. Builder

1.2.1. Zweck

Builder ist ein Interface, das Teile eines komplexen Objekts aufbaut.

Manchmal, wenn der Builder ein gutes Bild davon hat, was er bauen solle, dann kann dieses Interface aus auch einer abstrakten Klasse mit Standardmethoden bestehen (siehe Adapter).

Wenn du einen komplexen Vererbungsbaum für ein Objekt hast, ist es nur logisch, dass auch der Builder über eine komplexe Vererbungshierarchie verfügt.

Hinweis: Builder haben oft auch ein Fluent Interface, siehe z.B. der Mockbuilder in PHPUnit.

1.2.2. Beispiele

  • PHPUnit: Mock Builder

1.2.3. UML Diagramm

Alt Builder UML Diagram

1.2.4. Code

Du findest den Code auch auf GitHub

Director.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder;

use DesignPatterns\Creational\Builder\Parts\Vehicle;

/**
 * Director is part of the builder pattern. It knows the interface of the builder
 * and builds a complex object with the help of the builder
 *
 * You can also inject many builders instead of one to build more complex objects
 */
class Director
{
    public function build(Builder $builder): Vehicle
    {
        $builder->createVehicle();
        $builder->addDoors();
        $builder->addEngine();
        $builder->addWheel();

        return $builder->getVehicle();
    }
}

Builder.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder;

use DesignPatterns\Creational\Builder\Parts\Vehicle;

interface Builder
{
    public function createVehicle();

    public function addWheel();

    public function addEngine();

    public function addDoors();

    public function getVehicle(): Vehicle;
}

TruckBuilder.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder;

use DesignPatterns\Creational\Builder\Parts\Door;
use DesignPatterns\Creational\Builder\Parts\Engine;
use DesignPatterns\Creational\Builder\Parts\Wheel;
use DesignPatterns\Creational\Builder\Parts\Truck;
use DesignPatterns\Creational\Builder\Parts\Vehicle;

class TruckBuilder implements Builder
{
    private Truck $truck;

    public function addDoors()
    {
        $this->truck->setPart('rightDoor', new Door());
        $this->truck->setPart('leftDoor', new Door());
    }

    public function addEngine()
    {
        $this->truck->setPart('truckEngine', new Engine());
    }

    public function addWheel()
    {
        $this->truck->setPart('wheel1', new Wheel());
        $this->truck->setPart('wheel2', new Wheel());
        $this->truck->setPart('wheel3', new Wheel());
        $this->truck->setPart('wheel4', new Wheel());
        $this->truck->setPart('wheel5', new Wheel());
        $this->truck->setPart('wheel6', new Wheel());
    }

    public function createVehicle()
    {
        $this->truck = new Truck();
    }

    public function getVehicle(): Vehicle
    {
        return $this->truck;
    }
}

CarBuilder.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder;

use DesignPatterns\Creational\Builder\Parts\Door;
use DesignPatterns\Creational\Builder\Parts\Engine;
use DesignPatterns\Creational\Builder\Parts\Wheel;
use DesignPatterns\Creational\Builder\Parts\Car;
use DesignPatterns\Creational\Builder\Parts\Vehicle;

class CarBuilder implements Builder
{
    private Car $car;

    public function addDoors()
    {
        $this->car->setPart('rightDoor', new Door());
        $this->car->setPart('leftDoor', new Door());
        $this->car->setPart('trunkLid', new Door());
    }

    public function addEngine()
    {
        $this->car->setPart('engine', new Engine());
    }

    public function addWheel()
    {
        $this->car->setPart('wheelLF', new Wheel());
        $this->car->setPart('wheelRF', new Wheel());
        $this->car->setPart('wheelLR', new Wheel());
        $this->car->setPart('wheelRR', new Wheel());
    }

    public function createVehicle()
    {
        $this->car = new Car();
    }

    public function getVehicle(): Vehicle
    {
        return $this->car;
    }
}

Parts/Vehicle.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder\Parts;

abstract class Vehicle
{
    public function setPart(string $key, object $value)
    {
    }
}

Parts/Truck.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder\Parts;

class Truck extends Vehicle
{
}

Parts/Car.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder\Parts;

class Car extends Vehicle
{
}

Parts/Engine.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder\Parts;

class Engine
{
}

Parts/Wheel.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder\Parts;

class Wheel
{
}

Parts/Door.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder\Parts;

class Door
{
}

1.2.5. Теst

Tests/DirectorTest.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Builder\Tests;

use DesignPatterns\Creational\Builder\Parts\Car;
use DesignPatterns\Creational\Builder\Parts\Truck;
use DesignPatterns\Creational\Builder\TruckBuilder;
use DesignPatterns\Creational\Builder\CarBuilder;
use DesignPatterns\Creational\Builder\Director;
use PHPUnit\Framework\TestCase;

class DirectorTest extends TestCase
{
    public function testCanBuildTruck()
    {
        $truckBuilder = new TruckBuilder();
        $newVehicle = (new Director())->build($truckBuilder);

        $this->assertInstanceOf(Truck::class, $newVehicle);
    }

    public function testCanBuildCar()
    {
        $carBuilder = new CarBuilder();
        $newVehicle = (new Director())->build($carBuilder);

        $this->assertInstanceOf(Car::class, $newVehicle);
    }
}