SimplyHover: Improving Comprehension of else Statements

Code comprehension is a vital mental process in any maintenance activity. It becomes decisive in large code blocks, in particular those that are governed by if-else statements. These large blocks increase the spatial distance between the if statement and its else counterpart or other dependent else statements. This increased spatial complexity makes it hard for the developer to recall the if logical expression that he has just read and understood, so he needs to go back and read it again, then understand it, and eventually negate it to get the else implicit logical expression. In extreme cases the if-else pair might occur in different pages so the developer has to scroll back and forth to grasp them both. Furthermore, to understand the else implicit negated expression he might want to go back to the farthest if statement and understand the aggregated logical expression all the way to the else which makes the understanding of the else even harder. In this work, we introduce SimplyHover, a plug-in for the Eclipse IDE that brings the if condition next to its else counterpart or one of its descendants saving the developer to go back and forth over and over again. Furthermore, SimplyHover presents to the developer, when he hovers over else, the if conditions in their negated form and even lets him write his own simplification for that. In some cases, the tool even suggests its own simplification of the aggregated expression. To demonstrate the usage and usefulness of SimplyHover, a few code snippets from real software are presented.