Package Interface

Previously, package interfaces could contain references to parallel interfaces of the same package, in addition to the objects of the package itself and propagated objects of the subpackages. The possibilities for accessing such combined interfaces, however, are difficult to describe as soon as access to the combined interface is allowed through dependency control lists, but access to some of the interfaces contained there is forbidden. Therefore, the aspects concerning the exposing of objects and grouping of interfaces will be treated separately.

Package interfaces of a package must contain solely either objects of the package itself or propagated objects from any usable package interface.

Exposing all objects of another package interface B by exposing a specific pseudo object that refers to B through a package interface A does not mean that B can be addressed by its original name by clients of A. Also, B's access control list doesn't affect clients of A, that is, B's access control list only controls whether A may expose B or not.

It will be possible to create interface lists to group package interfaces together. These lists consist of package interfaces of the same package or of interface lists of the same package. It is possible to have the interface list include, at any given time, the current set of all interfaces of the package.

Interface lists cannot define any use limitations. In this way, a dependency control list can be uniquely traced back - at any time - to a list of allowed package interfaces.

The following example illustrates the use of package interfaces:

Package Interfaces and Interface Lists

The objects a, b, and c are exposed in package interfaces G, H, and I. Interface list Y groups together package interfaces G and H; interface list Z groups together package interface I and interface list Y. In this way, Z finally groups together package interfaces G, H, and I.