YAGNI stands for “You Ain’t Gonna Need It” (yet).   It’s a mnemonic meant to remind us developers not to speculate. That we should only put in code that addresses the task at hand and worry about tomorrow’s challenges tomorrow. There are many good reasons for this advice, the chief among them being that situations may change between the time that the speculative development happens and the need for the feature actually arises. In that case, the speculative development will turn out to have been wasted development time that could have been spent on addressing more immediate problems.

I thought I had learned this lesson years ago. I thought I was pretty sensitive to YAGNI and had a good track record for resisting it. But, recently I introduced a bug in a system that I was working on, and the ultimate reason for the bug is that I had committed the “crime” of speculative development. Continue reading Lessons in YAGNI →