[Proposal] Decouple mutators / attribute casting from the Eloquent ORM

[andrzejkupczyk]

Wouldn't be great to encapsulate the attributes manipulation? That could be very useful eg. in the Request class. Regarding casting I thought of something as simple as:

• CastableContract
• CastableTrait

abstract class Model implements ArrayAccess, Arrayable, Castable, Jsonable, JsonSerializable, QueueableEntity, UrlRoutable
{
    use CastableTrait;
    …
}

class Request extends SymfonyRequest implements Arrayable, ArrayAccess, Castable
{
    use CastableTrait, Macroable;
    …
}

In combination with custom casting discussed in #16305 and #13706 it could be a very powerfull and yet a clean solution. Another approach could be a Processor/Transformer implementation (this is just a basic idea inspired by the need to encapsulate request data processing):

• Processable contract

interface Processable
{
    /**
     * Get the processed contents of the object.
     *
     * @return mixed
     */
    public function processed();
}

• an object/array could be also easily processed with a processor composite:

class ProcessableStack extends \SplObjectStorage implements Processable
{
    /**
     * Calculates an unique identifier for the contained processor.
     *
     * @param Processor $object
     *
     * @return string
     */
    public function getHash($object): string
    {
        return get_class($object);
    }

    /**
     * {@inheritdoc}
     */
    public function processed()
    {
        if (!$input = func_get_arg(0)) {
            return;
        }

        foreach ($this as $hash => $processor) {
            $input = $processor->run($input);
        }

        return $input;
    }
}

• examples of use:

$request->processedWith(UserUpdateRequest::class);
// or
$request->setProcessor(new UserUpdateRequest)->processed();
// or
$request->processed();

or maybe better interally by all(), input(), except() etc.?

[GrahamCampbell]

Thanks. Please open an issue on the internals repo to discuss this. We strictly only deal with isolated bug reports here.