Compared to the pre-GUI era, the typical workstation display these days is _ big_. We’re stocking new engineers with dual 1920x1200 widescreens. That’s the equivalent of six side-by-side VGA screens! In spite of this growth over the years, my basic monitor real-estate coding rules haven’t changed: stay within 80 columns, and try to keep each function short enough to fit vertically on a single screen.
The 80-column rule is a coding style convention that enhances readability and helps you play nice with your teammates. I’m not sure about the origin of the specific number 80, but it is the default width of a terminal window. A line of a typical book also happens to average 80 characters, and a book page is about the widest the human eye can read without getting lost in the middle. Whatever the exact limit is, it’s polite to stay within it because you don’t know the width of the window used by the person reading your code.
Resist the relentless pleas of your teammates to increase the 80-column limit. Wider monitors enable greater productivity by allowing activities you can’t do on smaller screens, like comfortably diffing two side-by-side GUI windows of 80-column code, or debugging an application while simultaneously stepping through its code. But you lose these new abilities if a wider monitor merely means that your code sprawls farther and farther to the right.
The height rule is more of an engineering principle than a mere style guideline, and as such, it’s more subjective. Just as long paragraphs in a book are tough to slog through because they contain too many ideas, long functions contain too much code to understand. Splitting one long function into smaller functions encourages documentation by forcing the programmer to give a (possibly) meaningful name to each new function. At the same time, the programmer will probably shorten the overall code by identifying repetitive, copy-paste code and replacing it with calls to a single general-purpose function.
I haven’t had to adjust my function-height rule over the years, but lately it’s making me feel lonely. I’m the lone engineer on my team who hasn’t rotated his LCD to portrait position. I see no reason to do so, because it’ll only make it easier to write longer functions.