How To Shutdown a Computer

Friday, January 16th, 2009

Sometimes I still feel like we’re in 1982 when it comes to really basic things like turning off a computer. Why do we have to select shutdown from a menu? Why do we have to carefully save each open file? Why don’t programs stop when we tell them to? (Time Machine has now been spinning for hours, and won’t stop even though I’ve told it to.) Why is this so much more complex than it needs to be?

In the future, here’s how shutdown should work:

  1. You flip the power switch.

That’s it. No shutdown menu item. No wait for the system to hibernate. No opportunity for applications to save data. Nothing.

In Praise of Draconian Error Handling, Part 1

Monday, January 12th, 2009

I’m doing a bit of work on XOM, trying to optimize and improve some of the Unicode normalization code. A lot of this is autogenerated from the Unicode data files, and I’m actually working on the meta-code that parses those files and then generates the actual shipping code. In this code, I’m setting up a switch statement like this one:

       switch(i) {
          case 0:
            return result + "NOT_REORDERED";
          case 1:
            return result + "OVERLAY";
          case 7:
            return result + "NUKTA";
          case 8:
            return result + "KANA_VOICING";
          case 9:
            return result + "VIRAMA";
          case 202:
            return result + "ATTACHED_BELOW";
          case 216:
            return result + "ATTACHED_ABOVE_RIGHT";
          case 218:
            return result + "BELOW_LEFT";
          case 220:
            return result + "BELOW";
          case 222:
            return result + "BELOW_RIGHT";
          case 224:
            return result + "LEFT";
          case 226:
            return result + "RIGHT";
          case 228:
            return result + "ABOVE_LEFT";
          case 230:
            return result + "ABOVE";
          case 232:
            return result + "ABOVE_RIGHT";
          case 233:
            return result + "DOUBLE_BELOW";
          case 234:
            return result + "DOUBLE_ABOVE";
          case 240:
            return result + "IOTA_SUBSCRIPT";
            return result + "NOT_REORDERED";

And then I stop myself. Do you see the bug? Actually it’s a meta bug that leads to the true bug.

Prefer Multiline if

Thursday, January 1st, 2009

C-family languages including Java, C#, and C++ do not require braces around single line blocks. For example, this is a legal loop:

for (int i=0; i < args.length; i++) process(args[i]);

So’s this:

for (int i=0; i < args.length; i++) 

However both of these are very bad form, and lead to buggy code. All blocks in C-like languages should be explicitly delimited by braces across multiple lines in all cases. Here’s why: