Guido sees the light: PEP 8 updated

[Rustom Mody]

On Monday, April 18, 2016 at 8:49:33 AM UTC+5:30, Steven D'Aprano wrote:
> On Mon, 18 Apr 2016 11:39 am, Rustom Mody wrote:
> 
> > yes we can agree on this -- arbitrary line lengths are almost certainly
> > unreadable.
> > The problem then becomes so what is optimal?
> 
> I really don't think it is a problem. We have about 400 years
> of experience with printed text, and that experience tells us
> that the optimal width for reading prose in Western languages
> is about 60 characters, give or take. This width is optimal
> for eye movement, and minimizes the number of errors and 
> reduces eye-strain.

No disagreement so far

> 
> There's only so far that our eyes can follow a line to the
> right without increasing stress or reading errors, and 
> likewise when returning back to the left margin. The longer
> the line, the higher the chance of losing track, and the
> physical effort it takes to read. (You have to move the eyes
> further, and for extremely long lines, you may have to move
> your entire head.)
> 
> Long lines are simply harder to read because you have to
> move your eyes more, and the longer the lines, the greater
> the tendency to wander across the lines. Especially if the
> lines are close together and the height of the lines is
> small. (It boggles my mind how many programmers I've met who
> routinely view their code in tiny physical heights, even
> when reading it in fine detail.)
> 
> The optimal width for eye-tracking (that is, the maximum
> width for which the rate of such errors can be disregarded)
> is somewhere about sixty characters per line.

Maybe even this is ok

> 
> The same eye-tracking considerations apply to code

This is nonsense.

The last attempt of making code text-ish was Cobol -- by most accounts an 
unhappy experience.
What is more code needs to be read very intensively for comprehension
"x... what is x where is it defined? (scan backwards) ah there?
Uh no further back... No global..."
My own estimate of increased back-n-forth scanning of code vs plain text is 
probably an order of magnitude ie close to 10 times
Even if I grant that you are twice as good a programmer as I am it will become
5 times.
You would have to be 10 times better than me to equalize to (my) plaintext rate
But if you are that kind of genius you probably speed-read plain text as well.

tl;dr 
1. Different languages -- natural and computer -- have different optimal line lengths.

2. There is very scant data on that.

3. PEP8 style strictures only delay discovery and collection of such data