Beyond the black box: open implementation

Encapsulation, informally known as black-box abstraction, is a widely known and accepted principle. It is a basic tenet of software design, underlying approaches to portability and reuse. However, many practitioners find themselves violating it in order to achieve performance requirements in a practical manner. The gap between theory and practice must be filled. Open implementation is a controversial new approach that claims to do just that. The paper provides some ideas to spark further debate on black-box abstraction.