The Shape of Code

Until today, to the best of my knowledge, all the source code analysis papers I have read were written by researchers who had control of the code analysis tools they used and had some form of localised access to the source. By control of the code analysis tools I mean that the researchers specified the tool options and had the ability to check the behavior of the tool, in many cases the source of the tool was available to them and often even written by them, and the localised access may have involved downloading lots of code from the web.

I have just been reading about a broad brush analysis of comment usage based on data provided by a commercial code repository that offers API access to some basic code metrics.

At first, I was very frustrated by the lack of depth to the analysis provided in the paper, but then I realised that the authors’ intent was to investigate a few broad ideas about comment usage in a large number of projects (around 10,000). The authors complained in their blog about some of the referees comments and having to submit a shorter paper. I can see where the referees are coming from, the papers are lacking in depth of analysis, but they do contain some interesting results.

I was very interested in Figure 2:

which plots the comment density of the lines in a source code commit. I would expect the ratio to be higher for small commits because a developer probably has a relatively fixed amount to say about updates involving a smallish number of lines (which probably fixes a problem). Larger commits are probably updated functionality and so would have a comment density similar to the ‘average’.

The problem with relying on third parties to supply the data is that obtaining the answers to follow up questions invariably involves lots of work, e.g., creating an environment to perform the measurements needed for the follow-up questions. However, the third party approach can significantly reduce the amount of work needed to get to a point where the interestingness of the results can be gauged.