I build accounting software and half my "what" comments are actually explaining business rules that would be impenetrable otherwise. Something like:

  // Bank transfers appear as two transactions - a debit here and credit elsewhere
  // We match them by looking for equal-opposite amounts within a 3-day window
  

The Uncle Bob approach of extractNameMatchingTransfersWithinSettlementWindow() doesn't actually help - now I need to know what settlement windows are anyway, and I've lost the context of why 3 days.

I don't know how that book ever got as big as it did, all you have to do is try it to know that it's very annoying and does not help readability at all.

When I read the replace() method, I was immediately confused because it has no arguments. stringToReplace and alreadyReplaced are properties of the class, so you must look elsewhere (meaning, outside of the function) for their definitions. You also don't know what other bits of the class are doing with those properties when you're not looking. Both of these facts inflate the context you have to carry around in your head.

Why is this a class? In the replace() method, there is a call to translate(symbolName). Why isn't there also a SymbolNameTranslator class with a translate() method? Who decided one was simple enough to use a function while the other warrants a class?

SymbolReplacer surely could also be done with a function. I understand that this is illustration code, so the usage and purpose is not clear (and the original Bob Martin article does not help). Is there a reason we want these half-replaced strings made available every time we call SymbolReplacer.replace()? If there is, we can get the same data by using a reduce function and returning all of the iterations in a list.

A plain, immutable function necessarily contains within it the entire scope of its behavior. It accepts and returns plain data that has no baggage attached to it about the data's purpose. It does one thing only.

I have no idea why people want to "save time" to write short comments and short variable names. I just CTRL+C, CTRL+V my variable name anyway. They compound on each other, and that ends up adding an unnecessary level of complexity, and the possibility for errors.

When I come back to a piece of complex code after a year or two, I'm very, very happy that I've used a variable name like "three_tuple_of_weight_radius_price" instead of "tuple" or "t".

There might be a better one that also takes into account whether the code does something weird or unexpected for the reader (like the duplicate clear call from the article).

Names capture ideas. Only if we name something can we (or at least I) reason about it. The more clear and descriptive a name for something is, the less cognitive load is required to include the thing in that reasoning.

TFA's example that "weight" is a better variable name than "w" is because "weight" immediately has a meaning while use of "w" requires me to carry around the cumbersome "w is weight" whenever I see or think about "w".

Function names serve the same purpose as variable names but for operations instead of data.

Of course, with naming, context matters and defining functions adds lines of code which adds complexity. As does defining overly verbose variable names: "the_weight_of_the_red_ball" instead of "weight". So, some balance that takes into account the context is needed and perhaps there is some art in finding that balance.

Comments, then, provide a useful intermediate on a spectrum between function-heavy "Uncle Bob" style and function-less "stream of consciousness" style.

Had to add the last sentence for the circa 2020s developer experience. LLM comments are almost never useful since they're supposed to convey meaningful information to another human coder, anything your human brain can think of will probably be more helpful context.

I hope not of a lot of the future folks hate me for leaving them with ample context and clear/dead simple code.

Replace symbol placeholders in the input string with translated values. Scan the string for symbol placeholders that use the format "$foo". The format uses a dollar sign, then optional ASCII letter, then optional word characters. Each recognized symbol is replaced with its corresponding value.

Symbols are only replaced if the symbol exists i.e. getSymbol(String) returns non-null, and the symbol has not already been replaced in this invocation.

Example:

  - input = "Hello $name, welcome to $city!"

  - output -> "Hello Alice, welcome to Boston!"

I'm trying to think of a good example, maybe something like a pointer window based function (off the top of my head)

(This isn't real code. Don't get hung up on it)

    func DedupeStrings(ss []string) []string {
      if len(ss) < 2 {
        return ss
      }
      ss = strings.Sort(ss)

      u := 1 // index of end of "uniques" set
      for i := 1; i < len(ss); i++ {
        // Consume until new value
        if ss[i] == ss[i-1] {
          continue
        }
        // Put new value in 'uniques' set
        ss[u] = sorted[i]
        u++
      }
      // Final state: all unique items are positioned 
      // left of 'u' index
      return ss[:u]
    }

- I'm not convinced you could change the variable names without harming clarity. Would a name like uniquesEndIndex really be any clearer? It adds noise to the code and still doesn't satisfy a confused reader

- I don't want to use function calls for documentation, eg putInUniques(). I'm doing it this way because I want it to run really quick.

If that needs a why it’s a why-comment.

If it needs a what it’s a what-comment. Especially if clever programming tricks are used. 6 month later you already forgot what the trick is and how it works.

If I look through code and see a variable I don't know, I want to see its definition anyway, so I know the type, scope, initial value, etc. And it's trivially possible to do that with everything that has a "jump to definition" command.

He starts implementing any module or function by first writing the documentation for it and let's it guide both the functionality and structure.

Makes Redis also extremely easy and enjoyable to read.

Random example: https://github.com/redis/redis/blob/unstable/src/aof.c

For example, for some reason padding bytes are allowed in variable length integers (LEB128) for reasons I still do not understand:

    // Allow padding bytes that do not affect the value
    let expectedBits: UInt8 = (result < 0) ? 0x7F : 0x00

    applyDrag(): void {
        const { quad: quadConfig } = settings
        const quad = this.getRigidBody()
        const quadVel = vec3ToTwgl(quad.linvel())
        const dragMag = aerodynamicDrag(quadConfig.dragCoefficient, v3.length(quadVel), quadConfig.frontalArea)
        const dragDir = v3.negate(v3.normalize(quadVel))
        const dragForce = v3.mulScalar(dragDir, dragMag)
        const dragImpulse = v3.mulScalar(dragForce, dt)
        quad.applyImpulse(vec3TwglToRapier(dragImpulse), true)
    }

While it leads to more things to read, which thus may take time, I feel that the benefits of using comments far outweighs the negative sides. This is even valid when comments are outdated usually. To me, adjusting and updating comments often was much easier and faster than describing something de-novo.

In the ruby land this is quite problematic because many do not use any comments. The result is a horrible code base. Getting people who wrote that code to use comments is often too late, as they already abandoned ruby in favour of another language, so I never buy the cop-out explanation of "the code is self-explanatory" - not even in ruby it is. Everyone can write horrible code.

Same goes for comments vs commit messages. It's a fact comments get outdated and then you have an even bigger problem whereas a commit message is always correct at the time it was made. But obviously again, no hard rules. Sometimes I feel it's better to write a comment, e.g. if it's something that is really important and won't change a lot.

Change my mind!

Thought-provoking article, nonetheless!

  // translate will replace all instances; only need to run it once

  // Replace all symbols

  String replaceAllSymbols() {

    a=$b
    b=oops

    input:  foo $a bar
    output: foo $b bar

    input:  foo $a bar $b
    output: foo oops bar oops

The sane thing would be to loop through building the output string, adding the replacement for each symbol as you go. Using String.replace and the alreadyReplaced map is just a bad idea. Also inefficient, as it and throws away strings and does a redundant search on each loop iteration.

Feels typical of this whole '90s-era culture of arguing over refactoring with Java design patterns and ornate styles without ever thinking about if the algorithm is any good.

Edit: also, consider $foo $foobar. It doesn't properly tokenize on replacement, so this will also be wrong.

Of course, be sensible and use good judgement :-)

But, that's what we're paid for, right?

In my early days I read a lot of "you should" "this is wrong". But code is an expressive medium, you can do things one way, or do it the other, you can write "amountOfEmployees" or you can write "ne" with an "#amount of employees" comment, either way is absolutely fine and you can use whichever depending on your priorities, tradeoffs or even your mood.

Also I used to obsess over code, (and there's a lot of material that obsesses about code), but after you become profficient at it, there's a cap on the returns of investing time into your codebase, and you start to focus on the product itself. There's not much difference between a good codebase and a marvelously polished codebase, so you might as well use the extra focuse on going from a bad UX to a neutral UX or whatever improvement you can make to the product.

Comments should explain. If it’s why, it’s why. If it’s what, it’s what. The point of comments is to explain, to the reader/editor, what the intent of the code is and how you chose to approach it. That’s it. No need to fight over what, why, how, who, etc.

If you have domain knowledge that helps support the code, maybe a link to further reading, by all means add it to comments please!

That comment is not helpful, because it's wrong. The translate() function just is some sort of lookup. It doesn't replace anything. It's the stringToReplace.replace() call that replaces all instances.

There have been so many times where I have commented _why_ I think some uncle bob-ism made the code unclear and the response is always:

> *Sends link to Clean Code, maybe you don't know about this?

No, I do, and I am allowed to disagree with it. To which they always clutch their pearls "How do you think you know better than uncle bob!?", this is a Well Established Pattern TM.

I don't think I know better than Uncle Bob, but I don't think Uncle Bob works on this codebase nearly as much as you or I.

I find that ends up being succinct and useful in the future.

- clean code one, for me it just reads easier, specific bits of the larger operation are not surrounded with noise coming from other bits like it is in the commenting "what" one. I can focus more on each step, and that can make it easier to spot a bug or to refactor/adjust/extend, as now I'm more like on a given page of Lego set instructions

- the commenting of "what" one - yeah, this obviously makes it quicker (but probably not easier) to see the larger picture. It has benefits, but I believe this helps more hacker/scripter kind of people than programmers

It makes it easier for dev's brain to parse the code e.g. to understand what code really does, while fattier but commented version makes it harder but tries to replace it with information about original coder's intentions. Which is maybe important too but not as important as code itself.

Not to forget that it's too easy to change code and leave comments obsolete.

Even in stupidest cases, like:

    // add two and two
    let four = two + two

Maybe that's me, but I rarely saw teams which over-document, under-documenting is usually the case. So if we ever meet in professional environment - comment away. Worst case scenario - I'll skim over it.

I used to comment in a similar way to claude/chatgpt, as in both the what and why. (although the why in LLMs is often lost. ) I used to comment as if it was for someone who didn't know the libraries very well. (ie me in two years time. Documentation at the previous place was utterly shite, so it was effectively a journal of discovery)

However, my commenting style is both what and why. My variable names can be longer than my FANG peers, mainly because I know that English not being a first language means that half arsed abbreviations are difficult to parse.

But effort is placed on not using fancy features, python mostly, so avoiding lambdas and other "syntactic sugar", unless they absolutely make sense. If I do use them, i have a comment saying _why_ I'm doing it.

Some of my colleagues were dead against any kind of commenting. "my code should be readable enough without it". They had the luxury of working on one bit for a few months, then throwing it away.

Only comments should explain what, variable names should only hint

The first example is perfectly fine, nobody has the time to derive or read a verbose formula involving the words 'weight', 'radius' and 'price'.

But I don’t think they’re worth it. My issue with “what” comments is they’re brittle and can easily go out of sync with the code they’re describing. There’s no automation like type checking or unit tests that can enforce that comments stay accurate to the code they describe. Maybe LLMs can check this but in my experience they miss a lot of things.

When “what” comments go out of sync with the code, they spread misinformation and confusion. This is worse than no comments at all so I don’t think they’re worth it.

“Why” comments tend to be more stable and orthogonal to the implementation.

I may want to communicate further information about the inhabitants or values of a particular type, without introducing extraneous or superfluous types:

    -- given a path to a PEM encoded PKCS#8 formatted RSA private key and a
    -- JWT Claims Set (RFC 7519) represented as a strict ByteString,
    -- return a strict ByteString representing a base64 encoded RSA256-signed JWS.
    generateJWT :: FilePath -> B.ByteString -> IO (Maybe B.ByteString)
    generateJWT fp claims = (fmap unJwt <$>) . (maybe (return Nothing) (fmap eitherToMaybe . encodeClaims) =<<)
                                             $ fromPKCS8 fp
      where eitherToMaybe = preview _Right
            encodeClaims  = (flip $ rsaEncode RS256) claims

"When" is occasionally a good question to answer in a comment, e.g. for an interrupt handler, and "Where" is also occasionally a good thing to answer, e.g. "this code is only executed on ARM systems."

The other three questions typically form a hierarchy: Why -> What -> How.

A simplistic google shows that "code comments" are next to "what" and "how" at about the same frequency as they are next to "why" and "what."

This makes some amount of sense, when you consider the usual context. "Why" is often an (assumed) obvious unstated business reason, "What" is a thing done in support of that reason, and "How" is the mechanics of doing the thing.

But with multiple levels of abstraction, _maybe_ the "What" inside the hierarchy remains a "What" to the level above it, but becomes a "Why" to the next level of "What" in the hierarchy. Or maybe the "How" at the end of the hierarchy remains a "How" to the level above it but becomes a "What" to a new "How" level below it.

Is it:

Why -> What/Why -> What/Why -> What/Why -> What -> How

or

Why -> What -> How/What -> How/What -> How/What -> How

In many cases the intermediate nodes in this graph could be legitimately viewed as either What/Why or as How/What, depending on your viewpoint, which could partly depend on which code you read first.

In any case, there are a few hierarchies with final "Hows" that absolutely beg for comments (Carmack's famous inverse square root comes to mind) but in most problem domains that don't involve knowledge across system boundaries (e.g. cache optimization, atomic operations, etc.), the final "How" is almost always adequately explained by the code, _if_ the reader understands the immediately preceding "What."

If I see a function "BackupDatabase()" then I'm pretty sure I already know both "Why" and "What" at the highest levels. "How" I backup the database might be obvious once I am reading inside the function, or the code might be opaque enough that a particular set of lines requires explanation. You could view that explanation as part of "How" the database is backed up, or you could view that explanation as "What" the next few lines of code are doing.

Again, this viewpoint might even partly depend on where you started. If you are dumped inside the function by a debugger, your question might be "What the heck is this code doing here?" but if you are reading the code semi-linearly in an editor, you might wonder "How is BackupDatabase() implemented?"