Few things

[Don Clugston]

Lionello Lunesu wrote:
> Don Clugston wrote:
>> Lionello Lunesu wrote:
>>>> 7) From the FAQ: 
>>>
>>>> Many people have asked for a requirement that there be a break
>>>  > between cases in a switch statement, that C's behavior of
>>>  > silently falling through is the cause of many bugs.
>>>  > The reason D doesn't change this is for the same reason that
>>>  > integral promotion rules and operator precedence rules were
>>>  > kept the same - to make code that looks the same as in C
>>>  > operate the same. If it had subtly different semantics, it
>>>  > will cause frustratingly subtle bugs.
>>>
>>>> I agree with both points of view. My idea: calling this
>>>  > statement differently (like caseof) instead of "switch"
>>>  > (like in Pascal), so you can change its semantics too,
>>>  > removing the falling through (you may use the Pascal
>>>  > semantic too).
>>>
>>> Sorry to hijack your point here, but this got me thinking:
>>>
>>> Why not use "continue" for seeping through to the next case 
>>> statement? DMD could then complain if a case does not end with 
>>> break/continue/goto/return and silently insert a assert(0) before 
>>> each case (the way it does for functions that return a value.)
>>
>> Doesn't
>>
>> for (c;;) {
>>   switch (c) {
>>   case 'a': continue;
>>   case 'b': break;
>>   }
>> }
>>
>> already have a meaning?
> 
> Yes, I've done that too, but honestly I'd be the first one to admit that 
> it isn't very clear. In fact, I'd go so far as to call it a reason to 
> attach a meaning to "continue" in a switch/case.

Including making it illegal. Since there's no short syntax to break out of out 
an outer loop from inside a switch, I don't see why a bare 'continue' is legal.
(actually the spec doesn't mention it, so it's a bit ambiguous).
Especially since "continue <identifier>;" and "break <identifier>;" exist, and 
are clearer.

> As mentioned, it would break existing code :(

Searching for "continue; case" on google gave many hits for C-family languages. 
So even if it didn't break any existing D code, it would still be a problem for 
porting from other languages. I think that's a show-stopper. Which is a shame, 
because I do like the idea.