Encapsulating a C++ Library

Encapsulation is the hiding of internal details from the user of an abstract data type, class or module. Encapsulating a class library requires more than combining a set of classes that are encapsulated individually. Libraries need to hide the details of how objects are created because some kinds of objects may be represented by composites as opposed to single instances. Implementation classes and members also must be hidden from the user of a library, even if this hiding conflicts with the user’s desire to reuse library code. In this paper, we present the encapsulation techniques used in the InterViews 3.1, a C++ class library for building user interfaces. These techniques have been formulated from the experience of building and releasing InterViews over a period of several years.