The problem with all discussions of good commenting style is that it's like debating good footware. Good for what? Office? Hiking in snow? Walking on the beach? Except that we have different footware for different uses but only one set of comments.

Having such a limited commenting syntax is like assuming one permanent type of footware and debating which one would be best. I'd much rather have a smarter commenting system.

I'm not talking about supplementary docs stashed elsewhere to gather dust. I'd like to have expandable comments right where they are needed but usable differently for a glance at familiar code or puzzling through unfamiliar code. Something very brief that doesn't clutter the code, a couple of words or no words at all, with an expansion arrow to something more detailed, expanding to something fully documented with links to everything.

And comments with scope (this comment applies to this line, this one to the function, this to a group of functions...) that actively use the scope. By active I mean that if you make any edits to code in the scope of a comment, that comment changes color or some other mechanism similar to a Git merge conflict: You changed the code without changing the comment, so check and make sure the comment says what you want and click OK. You don't have to fix the comments immediately for each edit. Make a few changes, test, make sure it's working, but when it is, you can see at a glance which comments need to be checked.

The general idea is instead of debating The Best Way to Comment, consider ways to improve the commenting system itself.

> (this comment applies to this line, this one to the function, this to a group of functions...)

This is probably the major reason I much prefer introducing new variables and functions solely so I can give them descriptive names over using comments. Comments aren't scoped so they're often ambiguous and imprecise compared to code, which also contributes to them becoming out-of-sync with the code over time. Comments above a function definition are generally better than comments inside a function for example as it's clearer what the scope is.

Inline graphviz annotations would be very nice. Store the text, IDE "codelens" renders it out

>The number of times I have been misled by an outdated comment

Imo a problem with code review and not leaving comments. Just like tests need changed during refactoring, documentation and comments should also be cleaned up as part of the change

I have found those as well but place the blame on the person who made the subsequent change and ignored them

There’s not many code review platforms that are great at showing you relevant comments in a diff because they are often in a much different part of the file, so I kind of think it’s hopeless in a large code base to catch this sort of thing in a code review

I now use VS code for reviewing PRs and it's easy to spot and then touch up comments.

With GitHub, not so much.

Not sure why code base size would make it harder... Workflow? Code unit size? The larger the code base, the more comment discipline matters IMO

I was mostly thinking about how small changes can sometimes touch a larger quantity of files on moderate or large code bases, so a bit more things to wade through when doing a review, but point taken.

Comments are not inherently bad but they do have inherent short comings. Still a useful tool but one that should be reached for rarely and last.

Comments are "reached for rarely and last". Whatever shortcomings comments have pale in comparison to being faced with and trying to figure out undocumented or too sparsely commented code, which, in my long experience, has been an order of magnitude more prevalent than sufficiently documented/readable code. Heck, even a wrong comment is sometimes preferable to no comment if it at least gives me a clue as to what the purpose of that section of code was at some point in its evolution.

I personally strive for code that can be read as a sentence, especially in complicated sections of code.

This sometimes leads to weird intermediate variables which might look superfluous, e.g. intermediates like:

foo_has_at_least_1 = len(foo) >= 1

(not a great example, usually it’s a bit more semantics. than that) but later code using those intermediates reads as english, which can reduce cognitive load when reading the code and obviate comments, and preconditions are more readily verified.

It’s literate programming and I prefer that to long comment blocks like those in some of the examples. All that said, it can be hard to get coworkers into such a habit, especially those who feel brevity and abbreviation is a virtue.

The problem comes not with what the code does but why the code exists in the first place.

The only time I ever feel the need to leave comments is to explain code that doesn't appear to be needed or isn't obvious why it exists. Usually this comes from agreed upon technical debt, short notice requirements with tight deadlines, or some other form of tradeoff.

"We're doing a simple check and throwing an exception here since we have work to introduce a more comprehensive permission system in xyz epic"

or something like

"There's a complicated race condition in xyz so we're doing a simple sleep here since the proper fix involves introducing a distributed lock"

Sure those types of things are cases you want to avoid but unfortunately you occasionally end up there anyway and leaving a short explanation about a compromise is better than ambiguous code that appears to serve no purpose

I dont think that held in the examples or a lot of what I have seen in practice once comments become the norm. Most classes should not need a comment in them at all. Most methods should be self-explanatory. A comment detailing every line of code is a huge smell.

…and on the reviewer(s) who accepted the code change even though the comments no longer match the code.

I agree, but git and most code reviewing tools I've used only show a few lines of surrounding context so the reviewers might not even realize there's a comment further up that needs updating.

Generally speaking, for all but the smallest of changes you should never only review the diff, but pop open the actual file on that branch (GitHub makes this fairly easy, I can't speak to other tooling) and consider the change in the context of the surrounding code. Does it contradict comments? Needlessly duplicate code from elsewhere in the file instead of creating a single function to be used in both places? Shadow variables confusingly? Add yet another 5 lines to a 100 line function instead of leaving the code better than it found it?

You can't really judge any of this if you're just eyeballing a diff. Diffs are just the starting point for a review, and while tooling could make this easier, the full file is always just a git checkout away.

That is how I feel about these comments.

In a vacuum I like them and when I bump into a piece of 10 year old code commented like this it is great.

There is one caveat however, they have to be meticulously maintained and always updated to reflect every change made to the code. It is a huge caveat because more often than not the comments are out dated and no longer reflect the actual code and at that point they are detrimental.

That's why Knuth had the idea of creating literate programs where documentation and code was maintained in a single block. Unfortunately, this idea was never used in large scale.

Have you ever tried to read the soup he created with code blocks rearranged to suit the generated text rather than any future maintenance coder?

Yeah, I think there's a fundamental problem with the implementation -- with small, single-file programs where the code can be written in a chronologically linear manner it works well. But with that there's no need for reordering logic, so much of the more complex parts of weaving are redundant. Scripts, for example, are pretty easy to set up as [for example] markdown files, which works great (particularly in a project that requires a set of helper scripts which need why communicated -- having a set of markdown files in a folder makes it IME much more ergonomic for other devs). Anything larger and it gets increasingly fiddly and (again IME) not worth it.

> If you can’t write expressive code why would you assume your English is much better?

Because English is optimized for communicating human intent?

I guess aside from assembly and very low level or highly specified languages aren’t programming languages as well?

In my experience, it's much easier to get just the right level of abstraction for quick reader comprehension in natural English, compared to any programming language.

I have to agree. Unit tests are some of the most helpful things I’ve used whilst refactoring the Libreoffice vcl module. In fact, I’m now at the stage where if I only move a class into a new header I’m writing a test that covers that class.

An example I’m currently working on is:

https://gerrit.libreoffice.org/c/core/+/121403/5/vcl/qa/cppu...

Yup, the rate limiter comments are unhelpful. A top level comment explaining the idea is fine (and very useful) but code should largely be self documenting.

Which it often is, but they still wrote a comment, leading to ridiculous stuff along the lines of

> // Returns None is x = 0

if x = 0 { return None }

To me, comments in code are like descriptions in a novel.

I would agree that comments which unnecessarily describe what is to come are bad, in the same way that a novelist should prefer to show, not tell, unless there is a compelling reason for the reader to keep that description in mind as the immediate events unfold.

But to require almost all comments gone in favour of well-named code and external docs feels wrong too, in the same way that one would probably not like to read a book with no chapter headings, no visuals, simply describing the story in a dry (but informative) language, and relying on cliffnotes for actual context.

And if you say code is more like a technical report than a novel, I will disagree. Good code is always a pleasure to read, and typically for similar reasons that a good novel is pleasurable.

Agreed, I think that the code itself should be readable through better names, with the comments being a bonus rather than critical to the understanding of the code.

Exactly. In my opinion, Thinking Forth by Leo Brodie should be required reading for anyone who touches code.