Hello, internals!
Recently I was implementing some collections and realized that I cannot use ArrayAccess for immutable collections without throwing BadMethodCallException in offsetSet and offsetUnset. I also cannot have an interface ReadonlyCollection extends ArrayAccess, because offsetSet and offsetUnset are mutators and have TValue in a contravariant position.
Here’s the idea: let’s extract ArrayAccess::offsetExists and ArrayAccess::offsetGet methods into a separate ArrayAccessRead interface (name can be different) and allow read operations $exists = isset($object['key']) and $value = $object['key'] for objects of classes that implement this interface. ArrayAccess will then extend ArrayAccessRead and add the remaining 2 methods. Looks like this change should not break backward compatibility.
interface ArrayAccessRead
{
public function offsetExists(mixed $offset): bool;
public function offsetGet(mixed $offset): mixed;
}
interface ArrayAccess extends ArrayAccessRead
{
public function offsetSet(mixed $offset, mixed $value): void;
public function offsetUnset(mixed $offset): void;
}
// then interfaces of the doctrine/collections package might look like this:
namespace Doctrine\Common\Collections;
interface ReadableCollection extends Countable, IteratorAggregate, ArrayAccessRead {}
interface Collection extends ReadableCollection, ArrayAccess {}
···
Regards, Valentin Udaltsov
. Looking forward to news from Gina.