Code examples are of great value to programmers trying to learn an unfamiliar API. Effective code examples are often surrounded with plain text explanations of the relevant concepts, techniques, and API elements involved in the example. However, authoring concise yet complete explanations is a challenging balancing act. To address this challenge, we propose Casdoc, a novel authoring technique and presentation format for annotated code examples. Casdoc-formatted code examples are HTML documents designed to embed unobtrusive explanations into the code. They thus contain more explanations to address the varying needs of a larger audience, without disrupting individual readers with information they already know. Explanations are split into short annotations and organized into an intuitive tree-like structure, thus supporting a streamlined authoring process. We used Casdoc to produce 105 Java code examples as part of the course material for an undergraduate computer science course. Students preferred the new format over traditional code examples. Their interaction with code examples suggests that the intuitive structure of Casdoc annotations reduces the need for navigation aids such as search fields.
On-line tool and video: https://www.cs.mcgill.ca/~martin/casdoc/