Design Hygiene

Without ongoing attention to design hygiene, design integrity is bound to deteriorate over time. My latest IEEE design column, Enabling Change, briefly examines what it takes to keep a code base ready to absorb new design changes.

At the very least you should leave code as clean as it was before you made a change (if not better). One credo that Scott Bain extols in his new book, Emergent Design, is whenever you touch the code “do no harm”. Do what you know to be best at the time (given the constraints you are under). Scott is a realist, but I like his stance on when to fight for one particular design approach over another, too. When you think it will be really difficult to refactor/cleanup the design later due to a poor design decision that is on the verge of being made now, argue for what you think now is a better solution.

But even with good intentions and experience, we need to refactor and rework our code as we refine our design ideas–and learn from the code. Yep, we should refactor. Continually. But we don’t always do so. Emerson Murphy-Hill, a Ph.D. student at Portland State and Andrew Black, a professor at Portland State wrote an intriguing paper, Refactoring Tools: Fitness for Purpose, that also appears in the upcoming issue of IEEE Software. They explain why in practice refactoring tools aren’t used as much as they should be and propose some principles that characterize successful regularly used refactoring tools. They also distinguish between “floss refactorings”–those which should be done a regular ongoing basis during programming in order to avoid more pain later on– from “root canal” refactorings. They found that refactoring tools could be better designed and point out some that are better designed for daily use than others.

Junk faxes, print cartridges and canceling-oh my!

Because two colored ink cartridges are empty (cyan and yellow), my black and white faxes have been piling up in my machine’s buffer. My fax-printer-scanner insisted on having non-empty color cartridges installed. But when there are no color print jobs that doesn’t make technical sense. I suspect other considerations drove this design decision. Print cartridges are where the money is. From a business sense it makes dollars and cents to insist that all cartridges are installed and in good working order before allowing the user to print anything.

But even more annoying was the difficultly I had stopping my printer from printing a month’s worth of buffered faxes! Glancing quickly at the buttons on my Brother MFC-885CW I noticed one labeled Clear/Back and another Stop/Exit. I pushed the Clear/Back button a couple of times to no avail, then decided I’d just let the faxes print. (Mild curiosity led me to receive 3 fax ads for discount health care, 3 for vacation deals in Cancun, an invitation to the Presidential Who’s Who among business and professional achievers, and a Neo-Tech stock market news report.)

There will always be competing values and design goals. Business and users’ goals don’t always match. An ethical usability designer should point out these conflicts and not let them slide. I know that might be pushing it, but someone should have strongly questioned whether it is better to demand all cartridges be installed or not.

But usability concerns don’t stop at defining how to accomplish some task or what constraints exist on initiating one. How to start, stop, pause, quit, and retry should be considered, too. Clear/Back and Stop/Exit? How confusing! I wanted to clear the print buffer and stop all printing. But perhaps I should have stopped printing first. But then what? What I wanted was to stop all printing and clear my printer’s internal buffer all in one easy to do action (I don’t read manuals when faced with an exception in real time). Maybe pressing Stop/Exit would’ve accomplished that. I’m not sure. If I remember, next time I’ll try that.

But what if I wanted to stop one fax job, but continue printing the others. Hm, maybe that Fax Preview button on the other side of the print console could come in handy. Grr. There isn’t just one path through an exceptional case that a user might want to pursue. They all need to be carefully considered. And too many buttons with small and potentially confusing labels don’t help me accomplish an emergency action in a hurry. I think Brother could do better by displaying alternate flow options on the console during printing (did I mention there is a display console on my printer?), but I’d have to get “trained”to look there. Since I don’t stand by my printer and watch it work enough to notice what kinds of informative messages it displays, it might’ve been telling me what my options are, and I just didn’t notice. Now that’s a tough problem to tackle. Not sure how to avoid frustrating inattentive users who don’t know to look for advice on how to logically push that missing big red cancel button. (I’ll take a closer look the next time my printer prints a fax to see whether it tells me anything).