Supporting Selective Undo in a Code Editor

Programmers often need to revert some code to an earlier state, or restore a block of code that was deleted a while ago. However, support for this backtracking in modern programming environments is limited. Many of the backtracking tasks can be accomplished by having a selective undo feature in code editors, but this has major challenges: there can be conflicts among edit operations, and it is difficult to provide usable interfaces for selective undo. In this paper, we present AZURITE, an Eclipse plug-in that allows programmers to selectively undo finegrained code changes made in the code editor. With AZURITE, programmers can easily perform backtracking tasks, even when the desired code is not in the undo stack or a version control system. AZURITE also provides novel user interfaces specifically designed for selective undo, which were iteratively improved through user feedback gathered from actual users in a preliminary field trial. A formal lab study showed that programmers can successfully use AZURITE, and were twice as fast as when limited to conventional features.