Improvement to switch-case statement

[Stewart Gordon]

> Stewart Gordon wrote:
>> Yigal Chripun wrote:
>> <snip>
>>> IMO, either the switch statement should remain the low level
>>> (effiecient) construct as in C, or replaced by a general mechanism of
>>> pattern matching. your solution is kinda between the two above options
>>> and I don't see the point of it.
>>
>> What would a "general mechanism of pattern matching" involve, and how
>> would it replace switch? Would it replace if as well?
>>
>>> I'd personally prefer pattern matching to be added to D and the switch
>>> to be deprecated and eventually removed from the language.
>>
>> I'd personally prefer my proposal from years ago to be taken seriously:
>> http://www.digitalmars.com/d/archives/22722.html
>>
>> ISTM silly to improve switch but at the same time keep it restricted to
>> the same old arcane syntax.
>>
>> Stewart.
> 
> I have several idea on this, nothing finished though:
> 
> the only reason for switch in the first place is an optimization in the 
> compiler, besides that, there is no need for it at all and everything 
> can be done with a bunch of if statements.
> 
> we basically need a way to group several if/case statements together and 
> make them refer the same variable.
> 
> here's a first attempt:
> 
> match (value) {
>   case(1) foo();
>   case(2..4) { foo(); case(3) foo3(); bar(); continue; }
>   case(5) {...}
>   case() {...} // this is the default case
> }

So you make the () required so that the {} can be optional.  At least 
it's consistent with most other control flow statements this way.

I'm not sure why you need to use up another keyword for this - switch 
would work fine.  At least, I don't think it would lead to any parsing 
ambiguity, though it might take quite a bit of lookahead to determine 
which switch syntax is being used.

Would continue jump straight into the next case block that is a sibling 
of the current one, whatever it may be, or what?  And where there are 
uncased statements at the same block level as cased statements, under 
what circumstances will they be executed?

Moreover, will "default" still be legal in place of "case()"?

Stewart.