Simulate a generic class in PHP

Question

I'm trying to implement a Results class that processes queries. So, simply put, you would have functions like this:

function all();
function first();
function paginate(int $perPage, int $pageNo = 1);

This works pretty well, the problem being that the IDE has no possible way of knowing the return type when this same results class is being used in multiple different query classes. Example:

UserQuery->results()->all() will return an array of User entities.

UserQuery->results()->first() will return a single User entity.

In some languages, you have generics, which means I could just use Results<User> in the UserQuery class and then my Results class could return T[] and T respectively.

One idea I had was to pass an empty entity as the constructor to the Results class and then try to use that property as the return type, but I couldn't figure this out. Is there any workaround to this? The main problem I'm trying to solve is IDE autocompletion and analysis, so a pure phpDoc solution is perfectly fine for my use case.

The only other workaround I can come up with is having to write a separate Results class for each entity type, which would prove to be exhausting.

Answer 1

I don't think there's a way to do exactly what you described, but in similar cases I would suggest using a proxy class for each Results type and document proper return types using phpDocumentor's @method. This solution has added value of having a great place for any type specific Results modifications and expansions. Here's an example:

abstract class Results
{
    function all(): array
    {
    }

    function first()
    {
    }

    function paginate(int $perPage, int $pageNo = 1): array
    {
    }
}

class User { }

/**
 * @method User[] all()
 * @method User first()
 * @method User[] paginate(int $perPage, int $pageNo = 1)
 */
class UserResults extends Results { }

class UserQuery
{
    /**
     * @var UserResults
     */
    private $results;

    public function __construct()
    {
        $this->results = new UserResults();
    }

    public function results(): UserResults
    {
        return $this->results;
    }
}

$userQuery = new UserQuery();
$test = $userQuery->results()->all();