Modern object-oriented methodologies recommend an evolutionary approach with free alternation between analysis, design and implementation. BETA has also a textual syntax for describing implementations. The underlying concepts are the same. BETA unifies class, procedure, generic class, process, exception, etc. into one abstraction mechanism, the pattern. In addition to class inheritance, subpatterns give method and process inheritance.
Nested patterns are useful for structuring large frameworks with hierarchical structures.
No special construct for exceptions. Concurrent Objects BETA has builtin concurrency in the form of active objects. The basic synchronization mechanism is the semaphore, but BETA's powerful abstraction mechanisms make it easy to define high-level concurrency abstractions on top of semaphores. Distributed Objects Objects can be distributed in a network. Access to distributed objects is transparent and looks the same as for local objects.