the current top post on Hacker News is PySnooper, a cute and useful tool that straddles the middle line between robust debugging and throwing in
print(foo) every few lines like you’re salt bae. the readme features, as marketing, the situation in which it may be found useful (emphasis mine):
You’re trying to figure out why your Python code isn’t doing what you think it should be doing. You’d love to use a full-fledged debugger with breakpoints and watches, but you can’t be bothered to set one up right now.
the top comment on this post is a paean to
Happy to see new tools for debugging. Yet it’s the good old print that I most often end up using. Debugging is very context-sensitive: adding prints makes sense because I know exactly what I’m interested in, and I can drill down on that without being disturbed by anything else. I can print low-level stuff or high-level indicators, depending where my debugging takes me. There’s no ready-made recipe for that. Some codebases have built-in logging or tracing functionality: you just flick a switch in a module and begin to get ready-made prints from all the interesting parts. But I’ve found myself never using those: they are not my prints, they do not come from the context I’m in and they don’t have a meaning.
Use what you want but please don’t underestimate prints.
and this sentiment is pretty broad, both among front-end and back-end developers:
This has been my debugging strategy for the past 10 years and I don't see it changing pic.twitter.com/E9cm3p1Pkj— Sebastian McKenzie (@sebmck) March 24, 2019
i understand this, and find myself sympathizing with this a lot. printing is easy; printing feels natural in the same way using a REPL to test feels natural. it is something i have done for literally the majority of my life, compared to the modernism and effort and constraint of connecting with a debugger.
and truth be told, there was a very long time where i didn’t know how to debug well. like, i understood it in the abstract and academic sense — having used
valgrind in college — but it was never a thing that i considered a tool with which i could more capably solve problems. it was a thing a different type of engineer did.
but there has been no single greater improvement to my debugging productivity than using a debugger enough to turn it into muscle memory — and i am not even “good” at debuggers. i have merely achieved a level of baseline competence easily available to anyone with an hour or two of spare time.
there are cases where I find myself leaning to use print statements over a formal debugger. “it’s gotta be just this variable”, i tell myself. “just a sanity check.”
and this is the same voice i use when I say “i’m sure this doesn’t need a test” or “i know this migration will just work fine.” a lot of my maturation as a developer has come from realizing that intuition is a disease and a crutch rather than a thing that should be relied on in lieu of formal verifications: the goal should be to delay intuition until it is reified in a thing that exists beyond your mind. 1
it’s never just that variable; i am wrong so many more times than i am right. a proper debugger gives you line-by-line execution, variable watching, arbitrary code evaluation, and much more. it is really valuable and i encourage you to make debugging more of a habit! it is fun and fast and easy and will make you better at your job.