I’ve done a little bit of work lately on a utility that reads from log files that are generated over the course of a month. Probably about 98% of the time, users would only be interested in this month’s file and last month’s file. How should I handle this?
At different points in my career, I’d have answered this question differently. Early on, my answer would have been to ignore the sentence about “98% of the time” and just implement a solution wherein the user had to pick which file or files he wanted. For a lot of my career, I would have written the utility to read this month and last month’s files by default and to take an optional command line parameter to specify a different file to read (“sensible defaults”). These days, my inclination is more toward just writing it to read this month’s and last month’s file, shipping it, and seeing if anyone complains — seeing if that 2% is really 2% or if, maybe, it’s actually 0%.
Part of this evolution in me was the evolution of the software industry itself. When I started out doing a lot of C and C++ in the Linux/Unix worlds, gigantic documents and users’ manuals were the norm. If you were a programmer, it was your responsibility to write massive, sprawling APIs and if you used someone’s code, it was your responsibility to use those massive APIs and read those gigantic manuals. So, who cares what percentage of time a user might do what? You just write everything that could ever possibly happen into your code and then tell everyone to go read the manual.
Then things started to get a little more “agile” and YAGNI started to prevail. On top of that, the user became more of a first class citizen, so “let’s default to the most common path” became the attractive thing to do and “RTFM” went the way of the dodo. The iconic example would be a mid 2000’s Windows or web application that would give you a sensible experience and then offer a dizzying array of features in some “Advanced Settings” window.
The next step was born with the release of the iPhone when it started to become acceptable and then normal to write dead simple things that didn’t purport to do everything. Apple’s lead here was, “this is the app, this is what it does, take it or leave it.” The “advanced settings” window was replaced by “we’ll tell you what settings you want,” which requires no window.
This shifting environment over the last 15 years informed my perspective but wasn’t entirely responsible for it. I’d say what was responsible for the shift were two realizations. First, I realized, “a ‘business spec’ isn’t nearly as important as understanding your users, their goals, and how they will use what you give them.” It became important to understand that one particular use case was so dominant that making it a pleasant experience at the cost of making another experience less pleasant was clearly worthwhile. The second realization came years later, when I learned that your users do, frequently, want you to tell them how to use your stuff.
Some of this opinion arose from spending good bits of time in a consulting capacity, where pointing out problems and offering a handful of solutions typically results in, “well, you’re the expert — which one should I do?” You hear that enough and you start saying instead, “here’s a problem I’ve noticed and here’s how I’ve had success in the past fixing this problem.” It makes sense when you think about it. Imagine having someone out to fix your HVAC system and he offers you 4 possible solutions. You might ask a bit about cost/benefit and pros/cons, but what you’ll probably wind up saying is, “so…. what would you do and/or what should I do?”
There’s an elegance to coding up what a user will do 98% of the time and just shipping that, crude as it sounds. As I mentioned, it will confirm whether your “98%” estimate was actually accurate. But, more importantly, you’ll get a solution for 98% of the problem to market pretty quickly, letting the customer realize the overwhelming majority of ROI right away. On top of that, you’ll also not spend a bunch of money chasing the 2% case up front before knowing for sure what the impact of not having it will be. And finally, you add the possibility for a money-saving work-around. If the utility always reads this month’s and last month’s files, and we need to read one from a year ago… rather than writing a bunch of code for that… why not just rename the file from a year ago and run it? That’ll cost your client 10 seconds per occurrence (and these occurrences are rare, remember) rather than hundreds or thousands of dollars in billable work as you handle all sorts of edge cases around date/time validation, command line args, etc.
I always wince a little when I offer anecdotes of the form, “when I was younger, I had position X but I’ve come to have position Y” because it introduces a subtle fallacy of “when you get wiser like me, you’ll see that you’re wrong and I’m right.” But in this case, the point wasn’t to discredit my old ways of thinking, per se, but rather to explain how past experiences have guided the change in my approach. I’ve actually stumbled a fair bit into this, rather than arrived here with a lot of careful deliberation. You see, there were a lot of times that I completely whiffed on considering the 2% case at all and just shipped, realizing to my horror only after the fact that I’d forgotten something. Bracing for getting reamed as soon as someone figured out that I’d overlooked the 2% case, I battened down the hatches and prepared to face the fire only to face… absolutely nothing. No one noticed or cared, and the time spent on the 2% would have been a total waste.
So next time you find yourself thinking about how to handle some bizarre edge case or unlikely scenario, pull back and ask yourself whether handling that is worth delaying the normal cases or not. Ask yourself if your user can live with a gap in the edge case or work-around it. And really, ask yourself what the ROI for implementation looks like. This last exercise, more so than learning any particular framework, language or library, is what distinguishes a problem solver from a code slinger.