SERG Lunch: A Simple Implementation of the Delta Maintainability Model

The Delta-Maintainability Model (DMM) offers a methodology for assessing the way an individual commit affects the maintainability of a system. In a nutshell, the DMM measures the proportion of low-risk change in a commit. The resulting value ranges from 0.0 (all changes are risky) to 1.0 (all changes are low risk). It rewards making methods better, and penalizes making things worse.

Recently, we implemented a simple version of the DMM as part of PyDriller, the open source git repository mining tool.

In this talk, we walk through the Delta-Maintainability Model, discuss the implementation choices made, offer a comparison with the (more robust) DMM implementation provided by SIG, and explore its application to a number of open source systems.

This is based on joint work with Marco di Biase and Magiel Bruntink from the Software Improvement Group.

See also:

1. Marco di Biase, Ayushi Rastogi, Magiel Bruntink, and Arie van Deursen. The Delta Maintainability Model: measuring maintainability of fine-grained code changes. IEEE/ACM International Conference on Technical Debt (TechDebt) at ICSE 2019, pp 113-122 (online).

2. The PyDriller documentation of the DMM.

3. Davide Spadini, Maurício Finavaro Aniche and Alberto Bacchelli. PyDriller: Python framework for mining software repositories. ESEC/SIGSOFT FSE 2018: 908-911 (online).