Repo-Entity.php

<?php

final class Repository
{
  public save(Entity $item) {}
  public find($criteria): Entity {}
  public __construct(PDO $db) {}
}

final class Entity
{
  private $state = [];
  public static createFromState(array $state): static
  {
    $self = new static();
    $self->state = $state;
    return $self;
  }
  public saveState(): array
  {
    return $this->state;
  }
// Magic
  private function __construct(){}
  public function __set_state(array $state): static
  {
    return static::createFromState($state['state']);
  }
}