Comments on: Why Can’t I Switch Around Strings?

By: Oktal

Oktal — Sun, 10 Dec 2006 04:17:48 +0000

In C you can only switch on integer types, because I believe it’s implemented as a JMP instruction with a table, or something. *I* know what I’m trying to say, anyway :P

In Java, strings are objects, so you’d need to have some special cunning thing to do it. If it was implemented as loads of isEqual() calls (or whatever it’s called… been too long) then it wouldn’t have any speed benefit over a chain of if/else if’s (the main reason to use switch in C). It could use some sort of tree search, but that would be tough to generalise to classes other than string.

{
option1 => sub { result1; },
option2 => sub { result2; }.
option3 => sub { result3; },
}->{$inputvalue}->();

That’s Perl; I think Jonny’s Python thing used basically the same method.

By: bLaXe

bLaXe — Fri, 01 Dec 2006 16:01:37 +0000

Well – there’s already a switch statement in Java – but you can only switch around ints (or types which can be cast to ints).

I found that Elharo (the guy who wrote XOM) mentioned this when talking about things he would change in Java. At least I’m not the only one :)

By: Jonny

Jonny — Fri, 01 Dec 2006 15:17:35 +0000

In all seriousness: When I was doing some work in python, I was rather upset by its lack of switching and stumbled upon this site:

http://simon.incutio.com/archive/2004/05/07/switch

Simon details how to create switch functionality without a switch function – maybe it’s of help, maybe I’m waaay off on this one :)

By: bLaXe

bLaXe — Thu, 30 Nov 2006 17:46:20 +0000

Dude…..lame…..

By: Jonny

Jonny — Thu, 30 Nov 2006 14:11:30 +0000

Not sure what to say, other than this: http://youtube.com/watch?v=fhlqY145tpU should cheer you up :)