TR-129: Eva: An Event Driven Framework for Building User Interfaces in Smalltalk

Abstract

Eva is an event driven framework for implementing user interfaces in multiprocessor Smalltalk systems. Most current user interfaces systems (e.g., Smalltalk, MacApp and NeWS), while event based, use polling and coroutines to handle user interaction. This makes them hard to understand and difficult to use in multiprocessor environments. Eva uses events to drive the Actors (light weight processes) which make up the user interface. The components of the user interface are constructed from parts rather than by inheritance. This structure increases modularity and allows the interface to be distributed over several processors. Comprehensive event management and synthesis simplify the creation of new parts. Eva is useful in both uni-and multiprocessor systems.