1.2. Builder¶
1.2.1. Purpose¶
Builder is an interface that build parts of a complex object.
Sometimes, if the builder has a better knowledge of what it builds, this interface could be an abstract class with default methods (aka adapter).
If you have a complex inheritance tree for objects, it is logical to have a complex inheritance tree for builders too.
Note: Builders have often a fluent interface, see the mock builder of PHPUnit for example.
1.2.2. Examples¶
- PHPUnit: Mock Builder
1.2.3. UML Diagram¶

1.2.4. Code¶
You can also find this code on GitHub
Director.php
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | <?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
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | <?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
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | <?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
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | <?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;
}
}
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Parts/Vehicle.php
1 2 3 4 5 6 7 8 9 10 11 12 | <?php
declare(strict_types=1);
namespace DesignPatterns\Creational\Builder\Parts;
abstract class Vehicle
{
public function setPart(string $key, object $value)
{
}
}
|
Parts/Truck.php
1 2 3 4 5 6 7 8 9 | <?php
declare(strict_types=1);
namespace DesignPatterns\Creational\Builder\Parts;
class Truck extends Vehicle
{
}
|
Parts/Car.php
1 2 3 4 5 6 7 8 9 | <?php
declare(strict_types=1);
namespace DesignPatterns\Creational\Builder\Parts;
class Car extends Vehicle
{
}
|
Parts/Engine.php
1 2 3 4 5 6 7 8 9 | <?php
declare(strict_types=1);
namespace DesignPatterns\Creational\Builder\Parts;
class Engine
{
}
|
Parts/Wheel.php
1 2 3 4 5 6 7 8 9 | <?php
declare(strict_types=1);
namespace DesignPatterns\Creational\Builder\Parts;
class Wheel
{
}
|
Parts/Door.php
1 2 3 4 5 6 7 8 9 | <?php
declare(strict_types=1);
namespace DesignPatterns\Creational\Builder\Parts;
class Door
{
}
|
1.2.5. Test¶
Tests/DirectorTest.php
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | <?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);
}
}
|