Is it what really happened (lots of programmers, by mistake, wrote a comparison function which is just plain wrong), or Rob Pike is conjecturing?
It's somewhat easy to see how someone would make this shortcut when programming in C, but they weren't programming in C, they were programming in assembly (as the article describes). It's so much simpler to only check the first char when programming in assembly, so it's easier to see why the shortcut might've been taken.
For all intents and purposes at the time, it was a hack but it worked, and it worked well.
There was also a lot less code in general so I would expect every line to be considered in much more detail. Also, 'laziness' tends to be a character flaw that manifests itself everywhere in a person's work, not just in one place. And Richie/Kernighan don't exactly have a bad reputation.
I wonder if the '-a' parameter of ls appeared at the same time. If so it definitely wasn't an oversight.
In assembler `name[0]=='.'` is simple to write. Fetch what name points to and compare it to a literal `'.'`.
A function call on the other hand requires pushing registers to the stack, pushing the arguments to the stack, call the function, and then restoring the registers.
So if you are in a hurry and just want to try something, you will write the equivalent to `name[0]=='.'`.
I like to keep an eye on the costs of what code I'm writing to make sure I don't get too 21st century and let my codebase bloat until it's slow as molasses, but at the same time I happily harvest the benefits of usually not caring whether this function call is inlined or not, or caring about the exact number of cycles an indirect function call takes, etc. It's a delicate balance but worthwhile to cultivate it.
I think hiding files with a path convention is Good, Actually, but I'm comfortable being in the minority on that, and it's possible that if we instead had a hidden flag a la chmod permissions I would prefer that.
With "hidden" being a file attribute (like on MS-DOS), you'd have the risk of a filename collision with a file that you don't know is there.
> It was in assembler then, but the code in question was equivalent to something like this:
> if (name[0] == '.') continue;
> This statement was a little shorter than what it should have been, which is
> if (strcmp(name, ".") == 0 || strcmp(name, "..") == 0) continue;
There's no strcmp() in the first example.
if (name[0] == '.') {
if (name[1] == 0) continue;
if (name[1] == '.' && name[2] == 0) continue;
}