Design walkthroughs

Interested in knowing about another way to improve your software quality? This post from Project Smart captures some best practices for design walkthroughs. Although written with designers in mind, design walkthroughs of this type can work equally well for small teams of developers, particularly when making changes to mature, well-established software systems.

By scheduling a design walkthrough for a significant change to the application, be it an enhancement or a major bug fix, a design walkthrough enables the developer to get more eyes looking at the proposed change. By catching design oversights early in the process, it can reduce rework and frustration for the developer, and improve code stability and maintainability in the long-term for the entire team. It also has the benefit of exposing more members of the team to more of the code base.

Working as a senior developer for a small but effective software development team in the ’90s, we countered some quality issues in our software by implementing both design and implementation walkthroughs. The sequence of steps looked something like this:

1. A developer investigates the change required, and comes up with a design for the change – the existing classes involved, the refactoring required, any new interfaces or classes required, and so on.
2. The developer prepares a 20-min overview of the proposed changes and their impact on the current code base.
3. A design walkthrough occurs wherein the developer presents the overview and receives the feedback of the team
4. With the feedback in hand, the developer makes the change, noting where the implementation varies from the proposed changes as they work through any unanticipated changes required as they go
5. An implementation walkthrough is held when the change is complete, which provides the developer and the team a chance to review the change, and to understand any differences between the original change discussed and the implementation delivered in the end.

In this way, working with both a design and implementation walkthrough, a team can make best efforts to “plan-do-check-act” on significant changes to the system, and enhance the long-term viability of the application code base.