Re: Switch/Case statements revisited

[Ralph Hempel <rhempel@...>]

Fabien wrote:
> On Nov 7, 2007 3:05 PM, Jeremy Darling <jeremy.darling@gmail.com 
> <mailto:jeremy.darling@gmail.com>> wrote:
>
>     I like the fall through abilities of C and wish that they existed in
>     pascal without having to
>     hack them into place.
>
>
> I think most C developers will agree that unwanted fall-through are a 
> dangerous cause of bugs, so if it were really required it should at 
> least require a dedicated keyword, so that it doesn't happen by accident.

I've just gone over some C code I wrote to see what tradeoffs I could
see in switch and if/else useage.

One of the interesting outcomes was that I was able to consolidate
a lot of tests in one function that was essentially a big if/else
statement that returned one value indicating the state of the structure.

The result was used in a case statement in other functions, and I
ended up using (and commenting like crazy) the fallthrough feature
quite a bit.

> In my experience, it doesn't happen very often, and when there are 
> shared parts between cases, there is no case ordering in the switch that 
> satisfy all sharing constraints simultaneously.

Agreed. Once you get beyond more than a handful of cases things get
complicated very quickly...

I'm not sure there's a really compelling argument for switch in Lua.

Most C programmers are unaware of what the compiler is really doing
when it implements switch. In some cases, the result is a big nested
if/else, other times it does some range reduction and lookup.

In some ways, switch is just syntactic sugar for lookup tables or
a nested if as far as the compiler is concerned....

Ralph