switch break/fall (last minute request ... )

BCS BCS at pathilink.com
Mon Dec 25 17:27:01 PST 2006

Hasan Aljudy wrote:
> Maybe it's pointless asking this now, five days before v1.0, but I'll 
> give it a try.
> I would love it if there was a way to let the compiler catch the common 
> bug of forgetting a "break" statement after a case clause in a switch 
> statement.
> The C behavior of automatically falling through is a cause of many many 
> bugs. It's really easy to forget a break and it's not really easy to 
> discover this bug.
> I propose a new keyword, "fall", that would explicitly indicate the 
> coder's intention of allowing the switch statement to fall through to 
> the next case clause.
> The absence of either "fall" or "break" would indicate an error.
> Hypothetical example:
> ------------------
> switch( X )
> {
>   case A:
>        //something
>        fall;   <-- falls through to the next case
>   case B:
>        //something
>        break;  <-- break, same behavior as now
>   case C:
>        //something
>   case D:      <-- error, no break or fall statement before case D
>        //something
>        break;
> }
> -----------------

banning fall through but retaining "goto case;" and "goto case value;" 
would have the same effect. But for some reason I like your suggestion 
better. However, I'd rather just leave it all as it is.

What we need is a D-lint tool that would could enforce a set of 
"Optional requirements".  (Oh, cool name "D OptiOnal Requirements 
System", DOORS!!!!).

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