PHPStan examples

readme.md

PHPStan examples

Types

Using string-class<T> generic typehint with static as T

You can use static in generic to refer to the current class. This is useful in trait implementations:

/**
 * @template T
 */
class Factory {
    /**
     * @var class-string<T>
     */
    public $className;
    /**
     * @return T
     */
    public function createInstance()
    {
        // ...
    }
}

trait HasFactory {
    // Here you are using `static` to be `Person`, `Animal` or any class that use this trait
    /**
     * @return Factory<static>
     */
    public static factory(): Factory
    {
        // . . .
    }
}

class Person {
    use HasFactory;
    public $lastname;
}

class Animal {
    use HasFactory;
    public ?Person $owner
}

//...

$person = Person::factory()->createInstance();
$animal = Animal::factory()->createInstance();

echo $person->lastName; // No type error
$animal->owner = $person; // No type error

Complementing documentation at https://phpstan.org/writing-php-code/phpdoc-types#class-string

Ref: phpstan/phpstan#6314