Thursday, 22 November 2012

The Utility of Version Control Systems

In response to a post about the utility of version control systems.

The "backups" argument for version control is easily understood, but it is ultimately not that compelling. The real benefit that you get from version control is a dramatic cultural shift and a new way of working with collaborators.

First of all, a version control system provides a structured framework and vocabulary for collaboration and feedback. This means that it is possible to talk about "changes" and "branches'. This is not dissimilar from "track changes" functionality in MS Word. Secondly, it facilitates the implementation of automated services such as "continuous integration" and "continuous testing".

These two pieces of functionality enable a very significant cultural shift. In most domains, professionals are used to working independently for an extended period of time, only presenting results when they are finished, polished and (supposedly) error-free. This way of working leads to an intolerant attitude towards (rare) errors: The ensuing lack of humility creates and enforces a risk-averse culture. It quickly and inevitably becomes more important to be seen to be perfect than it is to innovate and solve problems.

The working culture and practices that version control systems and continuous integration support and encourage could not be more different. By publishing incomplete drafts and unfinished work, your mistakes and typos become part of the "public" record, along with a record of the way that you approach problems and do your work. This requires either a thick skin, or (more realistically) the realization that nobody really cares about your mistakes.

The benefit of this is strongest where the work being carried out by multiple professionals is highly interdependent. By sharing work earlier in the cycle, as well as more frequently, conflicts and misunderstandings are resolved up much sooner. In fact, it is highly likely that professionals that need to collaborate closely will already be using a form of version control (such as track changes) in their work already. Using tools like Subversion or Mercurial simply provides additional tools with finer grained control and a different approach to sharing and communication (changes pulled on demand from the repository rather than pushed out via email).

So, the prime benefit of version control is in the fact that it provides a structured framework for sharing work, as well as discussing and coordinating the collaborative development of documents that refer to, or otherwise depend upon, one another. Another, equally important benefit is that it encourages transparency and humility through the practice of regularly sharing unfinished work. Finally, as stated in the article, it acts as a record for understanding how work was carried out, and for recovering from past mistakes.