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2.9. Line Lengths

Use 78-column lines.

In these modern days of high-resolution 30-inch screens, anti-aliased fonts, and laser eyesight correction, it's entirely possible to program in a terminal window that's 300 columns wide.

Please don't.

Given the limitations of printed documents, legacy VGA display devices, presentation software, and unreconstructed managerial optics, it isn't reasonable to format code to a width greater than 80 columns. And even an 80-column line width is not always safe, given the text-wrapping characteristics of some terminals, editors, and mail systems.

Setting your right margin at 78 columns maximizes the usable width of each code line whilst ensuring that those lines appear consistently on the vast majority of display devices.

In vi, you can set your right margin appropriately by adding:

    set textwidth=78

to your configuration file. For Emacs, use:

    (setq fill-column 78)
    (setq auto-fill-mode t)

Another advantage of this particular line width is that it ensures that any code fragment sent via email can be quoted at least once without wrapping:

    From: boss@headquarters
    To: you@saltmines
    Subject: Please explain

    I came across this chunk of code in your latest module.
    Is this your idea of a joke???

    > $;=$/;seek+DATA,undef$/,!$s;$_=<DATA>;$s&&print||(*{q;::\;
    > ;}=sub{$d=$d-1?$d:$0;s;';\t#$d#;,$_})&&$g&&do{$y=($x||=20)*($y||8);sub
    > i{sleep&f}sub'p{print$;x$=,join$;,$b=~/.{$x}/g,$;}sub'f{pop||1}sub'n{substr($b
    > ,&f%$y,3)=~tr,O,O,}sub'g{@_[@_]=@_;--($f=&f);$m=substr($b,&f,1);($w,$w,$m,O)
    > [n($f-$x)+n($x+$f)-(${m}eq+O=>)+n$f]||$w}$w="\40";$b=join'',@ARGV?<>:$_,$w
    > x$y;$b=~s).)$&=~/\w/?O:$w)gse;substr($b,$y)=q++;$g='$i=0;$i?$b:$c=$b;
    > substr+$c,$i,1,g$i;$g=~s?\d+?($&+1)%$y?e;$i-$y+1?eval$g:do{$b=$c;p;i}';
    > sub'e{eval$g;&e};e}||eval||die+No.$;

    Please see me at once!!


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