Start implementing the Property API

Ok, commited an initial, largely hardcoded version of the entity property API.

The following part of the tests already work:

  public function testReadWrite() {
    $name = $this->randomName();
    $user = $this->drupalCreateUser();
    $entity = entity_create('entity_test', array('name' => $name, 'uid' => $user->uid));

    // Access the name property.
    $this->assertTrue($entity->name instanceof EntityPropertyInterface, 'Property implements interface');
    $this->assertTrue($entity->name[0] instanceof EntityPropertyItemInterface, 'Property item implements interface');

    $this->assertEqual($name, $entity->name->value, 'Name value can be read.');
    $this->assertEqual($name, $entity->name[0]->value, 'Name value can be read through list access.');

    // Change the name.
    $new_name = $this->randomName();
    $entity->name->value = $new_name = $this->randomName();
    $this->assertEqual($new_name, $entity->name->value, 'Updated Name value can be read.');

    // Access the user property.
    $this->assertTrue($entity->user instanceof EntityPropertyInterface, 'Property implements interface');
    $this->assertTrue($entity->user[0] instanceof EntityPropertyItemInterface, 'Property item implements interface');

    $this->assertEqual($user->uid, $entity->user->value, 'User id can be read.');
    $this->assertEqual($user->name, $entity->user->entity->name, 'User name value can be read.');

    // Change the assigned user.
    $new_user = $this->drupalCreateUser();
    $entity->user->entity = $new_user;
    $this->assertEqual($new_user->uid, $entity->user->value, 'User id can be read.');
    $this->assertEqual($new_user->name, $entity->user->entity->name, 'User name value can be read.');
  }

Saving doesn't work yet, because the properties are protected and then drupal_write_record() recieves EntityProperty objects and freaks out. But we will need to stop using that function anyway for the upcoming _property_data tables anyway.

As I understand we don't want to get rid of entity however, for these cases, the idea is that the object will provide convenience methods, so that you can do:

$entity->user()->name->value, or $node->author()->label().

Having the same method in multiple interfaces is fine as long as they don't conflict.

Having these e.g. is fine:

function get($name)
function get($name, $langcode = NULL)

This wouldn't work:

function get($name);
function get($name, $langcode);

The get/set methods from EntityInterface have an additional langcode, in other cases there is (or will be) additional documentation. And the validate()/access() methods are in parallel interfaces, which are, in the case of entity properties combined, but that's not required so that's why they are in both.

See the attached image, which contains a simple and incomplete class diagramm of all these classes.

Yes, as I said, the tests were passing for me. A least the ReadWrite tests.