The Grug Brained Developer (2022)

I’ve spent time at small startups and on “elite” big tech teams, and I’m usually the only one on my team using a debugger. Almost everyone in the real world (at least in web tech) seems to do print statement debugging. I have tried and failed to get others interested in using my workflow.

I generally agree that it’s the best way to start understanding a system. Breaking on an interesting line of code during a test run and studying the call stack that got me there is infinitely easier than trying to run the code forwards in my head.

Young grugs: learning this skill is a minor superpower. Take the time to get it working on your codebase, if you can.

> As personal choice, we tend not to use debuggers beyond getting a stack trace or the value of a variable or two. One reason is that it is easy to get lost in details of complicated data structures and control flow; we find stepping through a program less productive than thinking harder and adding output statements and self-checking code at critical places. Clicking over statements takes longer than scanning the output of judiciously-placed displays. It takes less time to decide where to put print statements than to single-step to the critical section of code, even assuming we know where that is. More important, debugging statements stay with the program; debugging sessions are transient.

I tend to agree with them on this. For almost all of the work that I do, this hypothesis-logs-exec loop gets me to the answer substantially faster. I'm not "trying to run the code forwards in my head". I already have a working model for the way that the code runs, I know what output I expect to see if the program is behaving according to that model, and I can usually quickly intuit what is actually happening based on the incorrect output from the prints.

[0] The unreasonable effectiveness of print debugging (349 points, 354 comments) April 2021 https://news.ycombinator.com/item?id=26925570

But... that's where you put breakpoints and then you don't need to "single-step" through code. Takes less time to put a breakpoint then to add (and later remove) temporary print statements.

(Now if you're putting in permanent logging that makes sense, do that anyway. But that probably won't coincide with debugging print statements...)

Printf debugging gives you the full picture of an entire execution at a glance, allowing you to see time as it happened. The debugger restricts you to step through time and hold the evolution of state in your memory in exchange for giving you free access to explore the state at each point.

Occasionally that arbitrary access is useful, but more often than not it's the evolution of state that you're interested in, and printf gives you that for free.