Is it possible to specify multiple return types on PHP 7?

php php-7 type-hinting
myol picture myol · May 4, 2016 · Viewed 50.7k times · Source

I have some methods that can return one of two return types. I'm using a framework utilizing MCV so refactoring these few functions in particular is not appealing.

Is it possible to declare the return type returning one or the other and failing on anything else?

function test(): ?
{
    if ($this->condition === false) {
        return FailObject;
    }

    return SucceedObject;
}

Answer

bishop picture bishop · May 4, 2016

As of PHP 8+, you may use union types:

function test(): FailObject|SuccessObject {}

The standard way, available in all versions since PHP 4, is for the two objects to share an interface. Example:

interface ReturnInterface {}
class FailObject implements ReturnInterface {}
class SuccessObject implements ReturnInterface {}
function test(): ReturnInterface {}

In this example, ReturnInterface is empty. Its mere presence supports the needed return type declaration.

You could also use a base, possibly abstract, class.

To me, for this use case, interfaces are more clear and more extensible than unikn types. For example, if I later want a WarnObject I need only to define it as extending ReturnInterface -- rather than going through all signatures and updating them to FailObject|SuccessObject|WarnObject.

Related questions

Nullable return types in PHP7

PHP 7 introduces return type declarations. Which means I can now indicate the return value is a certain class, interface, array, callable or one of the newly hintable scalar types, as is possible for function parameters. function returnHello(): string { return 'hello'; } …

Read More
Type hinting in PHP 7 - array of objects

Maybe I missed something but is there any option to define that function should have argument or return for example array of User objects? Consider the following code: <?php class User { protected $name; protected $age; /** * User constructor. * * @param $name */ …

Read More
Type hinting for properties in PHP 7?

Does php 7 support type hinting for class properties? I mean, not just for setters/getters but for the property itself. Something like: class Foo { /** * * @var Bar */ public $bar : Bar; } $fooInstance = new Foo(); $fooInstance->bar = new NotBar(); //Error

Read More