New in Symfony 7.1: TypeInfo Component

This is the first article of the series that shows the most important new features introduced by Symfony 7.1, which will be released at the end of May 2024.

Contributed by Mathias Arlaud and Baptiste Leduc in #52510

The PropertyInfo component extracts information about the types of PHP class properties using metadata from PHP reflection, Doctrine, PHPDoc, PHPStan, etc.

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readonly class Person
{
    public function __construct(
        public string $firstName,
    ) {
    }
}

$types = $propertyInfo->getTypes(Person::class, 'firstName');
/*
    $types = array(1) {
        [0] =>
            class Symfony\Component\PropertyInfo\Type (6) {
            private $builtinType          => string(6) "string"
            private $nullable             => bool(false)
            private $class                => NULL
            private $collection           => bool(false)
            private $collectionKeyType    => NULL
            private $collectionValueType  => NULL
        }
    }
*/

This component works well but it has two main limitations:

• It can't properly describe type unions, intersections or generics (this is partially solved by returning an array of Type objects);
• It can only get type information from properties and not from method arguments, return types, and raw strings.

That's why in Symfony 7.1 we're introducing a new TypeInfo component to solve these problems. The first problem is solved by defining a hierarchy of classes to describe the types (this will be expanded in the future with new classes when PHP adds new features related to types):

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Symfony\Component\TypeInfo\Type
├─ BuiltinType
├─ UnionType
├─ IntersectionType
├─ GenericType
├─ Template
└─ ObjectType
   └─ EnumType
      └─ BackedEnumType

The second problem is solved with a series of type information extractors that work not only on class properties (ReflectionReturnTypeResolver to get return types using PHP reflection; StringTypeResolver to get type information using PHPDoc annotations; etc.)

This component has been introduced as an experimental feature (meaning that its API could change a bit before considering it stable) but it's already in use inside the PropertyInfo component. In future Symfony versions we'll deprecate the Type class from PropertyInfo and all its related features in favor of the new Type class from TypeInfo component.