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On a tangent: Assuming the first line is "def largest_square_plot(width, height):", you may be interested to know that your code computes the greatest common divisor [1].

If I'd been the one to write this function, I would have done it like:

  def largest_square_plot(width, height):
    """Computes the largest square to tile a plot of the given width and height."""

    # because we want the grid of squares to fit exactly
    # the size of the squares needs to divide both width and height
    # to get the largest square, we use the greatest common divisor
    from math import gcd
    square_size = gcd(width, height)
    return (square_size, square_size)

... but now I realize that probably not everyone is intuitively familiar with the kind of math that involves the GCD, so your code is actually much more intuitive without that background.

[1] https://en.wikipedia.org/wiki/Greatest_common_divisor

I recently read an article that was linked from HN comments on a different topic. It spoke about how software is not about code or documentation but rather about building complex mental models of the systems, which the author called the Theory Building View. It was interesting to read but one thing popped into my head while reading it. Too often we make comments about what a function does, which may be necessary but is not sufficient. My light bulb clicked on and I thought that what we really need is to document the function's reason for existing. This doesn't change even if the code inside does and is the thing that you actually really care about as it gives you some idea about the architecture.

A good counter argument to Comments:

https://blog.codinghorror.com/coding-without-comments/

That article doesn't make a compelling case.

It suggests taking this code:

  // square root of n with Newton-Raphson approximation
  r = n / 2;
  while ( abs( r - (n/r) ) > t ) {
      r = 0.5 * ( r + (n/r) );
  }

  System.out.println( "r = " + r );

And refactoring it to this function:

  private double SquareRootApproximation(n) {
      r = n / 2;
      while ( abs( r - (n/r) ) > t ) {
          r = 0.5 * ( r + (n/r) );
      }
      return r;
  }

  System.out.println( "r = " + SquareRootApproximation(r) );

I'm all for this refactoring, but something was lost in the process. What kind of square root approximation is being used? Does the algorithm have a name? What would I search for if I wanted to read more about it? That information was in the original comment.

There's an infinite amount of detail that's impossible to capture in a comment and which invariably changes over time and doesn't hold in the future.

For my team, the solution has been writing longer commit messages detailing not only what has changed, but also the why and other considerations, potential pitfalls and so forth.

So in this case, a good commit message might read like:

``` Created square root approximation function

This is needed for rendering new polygons in renderer Foo in an efficient way as those don't need high degree of accuracy.

The algorithm used was Newton-Raphson approximation, accuracy was chosen by initial testing:

[[Test code here showing why a thing was chosen]]

Potential pitfalls here include foo and bar. X and Y were also considered, but left out due to unclear benefit over the simpler algorithm. ```

With an editor with good `git blame` support (or using github to dig through the layers) this gives me a lot of confidence about reading code as I can go back in time and read what the author was thinking about originally. This way I can evaluate properly if conditions have changed, rather than worry about the next Chthulu comment that does not apply.

Now you have to look in two places for the information- the code and the commit messages.

How so? The code still documents what is happening, the commits however lay out the whys.

The point is that these two are separate questions, and that trying to use comments as a crutch to join the two religiously is a headache. It's impossible to keep everything in sync and I don't want to read needless or worse misleading information.

What's worse, in comments we often omit the important details such as why was the change made, what other choices were considered, how was the thing benchmarked, etcetc.

That said, comments still have a place. Just not everywhere for everything and especially not for documenting history.

I disagree. I think the "whys" belong in the comments- in fact, that's the most important part of the comment if the code is cleanly written. I don't want to be happily coding along, get to a glob and have to go to the repo pane, hunt for the commit that explains this particular thing, then read a commit message. Put it in a comment in the code. Pretty please.

That isn't actually important unless you have multiple algorithms, which is when you create an ISquareRootApproximator interface, and have NewtonRaphsonAlgorithm and any other classes implement it.

Then you can have them duke it out running identical unit tests in the profiler.

That creates a clean separation between the people who just need to know what a function does and those that need to know how that function works. People who just need an approximated square root fast can understand perfectly well what ISquareRootApproximator.ApproximateSquareRoot( r ) does, and don't necessarily care whether your "get me a square root approximator" function returns a NewtonRaphsonAlgorithm, or a CORDICAlgorithm, or a BitshiftsMagicNumbersAndLookupTablesAlgorithm, or something else, so long as it approximates a square root.

I won't speak for anyone else, but I've written some really good code but then I had a hard time understand what the heck I did after a year.

Joe's arguments are weak

* code should be readable <--- I agree

* good comments require good writers <---- not really, comments are for fellow programmers to read. If you want to document your APIs, yes, spend good time on it, and get feedback from your colleagues. Inline code comments are internal, so write in the most natural way possible. I've read "shit" and "fuck" before (see Firefox codebase, very funny).

* refactoring <--- I agree, but refactoring and documentation cannot be mutual exclusive. That's wrong.

* His example is way too simple. Try a more difficult approximation function.

Joe needs to realize that code produced at work is not meant for one single individual. If I leave, I want my co-workers and their future co-workers to have a good time navigate through codebase.

Use comments wisely, but don't avoid them! Adding 10 extra lines of comments to the file is better than a one-liner no one can understand. Let's not run a 100-line competition when we are writing code professionally. I shouldn't need to frustrate my reviewers and beg me to explain. Use newlines to make your code more readable as well.

> * refactoring <--- I agree, but refactoring and documentation cannot be mutual exclusive. That's wrong.

Commenting is in tension with refactoring, because nothing enforces that comments remain correct when code is refactored, so they tend to go wrong.

> Use comments wisely, but don't avoid them! Adding 10 extra lines of comments to the file is better than a one-liner no one can understand.

But worse than a one-liner everyone can understand. I think Joel has the right of it: write comments as a last resort when you can't make the code readable enough without them. But don't use them as a crutch to avoid fixing the code.

I think his example proves the opposite of what he intends. His example is just begging for a discussion of how the approximation actually works, edge case considerations, error bounds, assumptions, limitations, complexity, and references. At least that's what I would want if I was looking at it with fresh eyes. Sure, the author's contact info is a little tongue-in-cheek but without comments I can only know what the code does, not what it's supposed to do.

> I echo the author's point in "Review the code with its author in mind".

I don't understand how the rest of your post relates to that, although I think it's an interesting point and following discussion.

On the topic of reviewing code with the author in mind, I'm not sure I agree at all with the linked article. Does it matter who wrote the code in any way? Good code is good, and bad code is bad. It may be a helpful hint to remember the author was a senior engineer (who may "know more" than you do), but is it really something to keep in mind the entire time you review?

If you know your team well, it will help you keep an eye out for common mistakes they've made in the past. It may also help adjust your tone, as developers you've worked with for a long time will understand light humor or other well-intended comments that might be read as off-putting by newer devs.

The anti-pattern to avoid here is assuming code written by senior engineers is inherently "better" in some way than that by a junior. Yes, it typically is, but the code should speak for itself. Ad hominem assumptions add little value.

Similar to blind testing in musical auditions. http://gap.hks.harvard.edu/orchestrating-impartiality-impact...

FYI: If your variables are floats you will be splitting hair by the time this code terminates.