Comments on: I’d Rather switch Than Fight!

By: Martijn Laarman

Martijn Laarman — Thu, 13 Mar 2008 17:33:20 +0000

I only use switch’s fallthrough for grouping
switch(i) { case 3: case 6: dosomething() break; case 1: case 4: doSomethingElse(); break; default: doSomethingElseAllTogether() }

In such cases the fallthrough is easy to pick up and very a sementical solution.

When 3 needs to do somethingOdd() and doSomething() and 6 only needs to doSomething() i generally avoid, and thus agree with the artice, the usage of switch.

By: David Jones

David Jones — Thu, 13 Sep 2007 13:29:24 +0000

Ted, I'm not sure about fall through being switch's "cleverest feature", but it could be a reference to Duff's device. JavaScript saw fit to change switch (compared to the C version) by not allowing the case statements to be embedded in interior statements (as in Duff's device), but mysteriously didn't take to opportunity to remove fall through. Strange. switch in JavaScript has another "attractive nuisance" too (love the term). You can have non constant expressions in the case labels. Happily I seem to be the only one to have noticed that.

By: Jordan

Jordan — Tue, 08 May 2007 08:16:04 +0000

What if the “break” statement was on the same line as “case.” Would that make it more obvious?

switch(arg) {
case “”:

break; case “”:

case “”:

break; case “”:
}

By: Dustin Diaz

Dustin Diaz — Sat, 05 May 2007 02:10:32 +0000

I actually liked goto. It made looping easy in QBasic. Doesn’t ActionScript also have the notion of goto?

By: romiro

romiro — Thu, 03 May 2007 22:57:03 +0000

I always thought there was something fishy about that switch statement…I always felt dirty using it and never exactly could put my finger on it.

By: Lars

Lars — Mon, 30 Apr 2007 23:59:49 +0000

Since the fallthru is the exception rather then the rule, the ‘break’ in each case should be assumed and a ‘fallthru’ command used to explicitly break the rule (no pun intended). However it is dificult to retrospectively correct for poor design.

By: Brad

Brad — Mon, 30 Apr 2007 20:39:08 +0000

GOTO is evil because it allows you to get away with hairy coding

The hairy code I’m talking about is not something that’s “gotten away with,” but a result of an evolutionary process, of years of modification by a multitude of programmers given a myriad of requirements under many time constraints. You know, the real world.

And I compared GOTO to labeled breaks, which don’t all go to the same place.

By: johnnysaucepn

johnnysaucepn — Mon, 30 Apr 2007 09:25:33 +0000

Whether the code should be refactored to eliminate the hairy nest is another issue altogether.

Actually, it's the same issue! GOTO is evil because it allows you to get away with hairy coding, and makes it even hairier. I'm no fan of switch/break/fallthrough, but at least the break doesn't have to specify where to go next - all breaks go to the same place.

By: Brad

Brad — Sun, 29 Apr 2007 15:02:58 +0000

As an old Fortan guy, let me put in a good word for GOTO. Forgetting for a second that it’s just a branch statement, and that no matter the language all loop and if/switch/case/whatever statements get compiled down to branches, sometimes jumping out of hairy nested constructs is easier to figure out with a GOTO than with a series of labeled break statements. (Whether the code should be refactored to eliminate the hairy nest is another issue altogether.)

However, a computed GOTO really is evil.

By: Jeff

Jeff — Fri, 27 Apr 2007 15:24:21 +0000

The case you list is very useful and not bug-prone. It’s when there are lines of code but no break in between cases that things can get really tricky. Some languages (I’m pretty sure C# and Java do this) allow for your case while disallowing the general, tricky case.