User interfaces often account for a majority of application code and defects. High quality user interfaces come with equally high development costs – lower than the cost of multitudes of users coping with low quality user interfaces, but higher than the mild frustration experienced by any individual user. Thus, the economics of software lead to a situation where barely passable user interfaces abound. That most user interface code comes from bespoke attempts to implement vague human interface guidelines is a leading cause of high cost and low quality.
This thesis introduces a novel formalism for user interfaces based on ordered constraint systems. Using explicit models for the values and relationships in a user interface, several reusable algorithms are defined for rich user interface behaviors, including value propagation, dataflow visualization, pinning, scripting, command activation, widget enablement, and context-sensitive help. Developers can leverage provably correct implementations of such desirable features for free, raising the quality of user interfaces while lowering their production cost.
Some of these behaviors have been implemented in a JavaScript framework, Hot-Drink, for web user interfaces, and a C++ framework, Adam, for desktop user interfaces. Experiments have demonstrated higher developer productivity, fewer lines of code, fewer defects, and fewer components when compared to conventional user interface frameworks
