Builder

builder.md

Having said that let me add a bit about what telescoping constructor anti-pattern is. At one point or the other we have all seen a constructor like below:

public function __construct($size, $cheese = true, $pepperoni = true, $tomato = false, $lettuce = true) {
}

As you can see; the number of constructor parameters can quickly get out of hand and it might become difficult to understand the arrangement of parameters. Plus this parameter list could keep on growing if you would want to add more options in future. This is called telescoping constructor anti-pattern.

Programmatic Example

The sane alternative is to use the builder pattern. First of all we have our burger that we want to make

class Burger {
    protected $size;

    protected $cheese = false;
    protected $pepperoni = false;
    protected $lettuce = false;
    protected $tomato = false;
    
    public function __construct(BurgerBuilder $builder) {
        $this->size = $builder->size;
        $this->cheese = $builder->cheese;
        $this->pepperoni = $builder->pepperoni;
        $this->lettuce = $builder->lettuce;
        $this->tomato = $builder->tomato;
    }
}

And then we have the builder

class BurgerBuilder {
    public $size;

    public $cheese = false;
    public $pepperoni = false;
    public $lettuce = false;
    public $tomato = false;

    public function __construct(int $size) {
        $this->size = $size;
    }
    
    public function addPepperoni() {
        $this->pepperoni = true;
        return $this;
    }
    
    public function addLettuce() {
        $this->lettuce = true;
        return $this;
    }
    
    public function addCheese() {
        $this->cheese = true;
        return $this;
    }
    
    public function addTomato() {
        $this->tomato = true;
        return $this;
    }
    
    public function build() : Burger {
        return new Burger($this);
    }
}

And then it can be used as:

$burger = (new BurgerBuilder(14))
                    ->addPepperoni()
                    ->addLettuce()
                    ->addTomato()
                    ->build();

When to use?

When there could be several flavors of an object and to avoid the constructor telescoping. The key difference from the factory pattern is that; factory pattern is to be used when the creation is a one step process while builder pattern is to be used when the creation is a multi step process.