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Diviner Tech Docs PhabricatorExtendedPolicyInterface

interface PhabricatorExtendedPolicyInterface
Phorge Technical Documentation (Policy)

Allows an object to define a more complex policy than it can with PhabricatorPolicyInterface alone.

Some objects have complex policies which depend on the policies of other objects. For example, users can generally only see a Revision in Differential if they can also see the Repository it belongs to.

These policies are normally enforced implicitly in the Query layer, by discarding objects which have related objects that can not be loaded. In most cases this has the same effect as really applying these policy checks would.

However, in some cases an object's policies are later checked by a different viewer. For example, before we execute Herald rules, we check that the rule owners can see the object we are about to evaluate.

In these cases, we need to account for these complex policies. We could do this by reloading the object over and over again for each viewer, but this implies a large performance cost. Instead, extended policies make it efficient to check policies against an object for multiple viewers.

Methods

public function getExtendedPolicy($capability, $viewer)

Get the extended policy for an object.

Return a list of additional policy checks that the viewer must satisfy in order to have the specified capability. This allows you to encode rules like "to see a revision, the viewer must also be able to see the repository it belongs to".

For example, to specify that the viewer must be able to see some other object in order to see this one, you could return:

return array(
  array($other_object, PhabricatorPolicyCapability::CAN_VIEW),
  // ...
);

If you don't have the actual object you want to check, you can return its PHID instead:

return array(
  array($other_phid, PhabricatorPolicyCapability::CAN_VIEW),
  // ...
);

You can return a list of capabilities instead of a single capability if you want to require multiple capabilities on a single object:

return array(
  array(
    $other_object,
    array(
      PhabricatorPolicyCapability::CAN_VIEW,
      PhabricatorPolicyCapability::CAN_EDIT,
    ),
  ),
  // ...
);
Parameters
const$capabilityCapability being tested.
PhabricatorUser$viewerViewer whose capabilities are being tested.
Return
list<pair<wild, wild>>List of extended policies.