How to complex switch?

[KennyTM~]

On May 12, 11 20:04, matthew ong wrote:
> Hi KennyTM~,
>
> Some of the valid reason:
> 1) Less key stroke

Invalid,

switch (x = f()) {
   case x < 0: return -x
   default: return x
}

50 significant characters

auto x = f();
if (x < 0) return -x;
else       return x;

41 significant characters

> 2) Easier code generator to implement

Invalid. Both share the same structure.

     switch (x = <variable>) {
        case <condition>: <statements> break;
        case <condition>: <statements> break;
        default:          <statements> break;
     }

     auto x = <variable>;
          if (<condition>) { <statements>; }
     else if (<condition>) { <statements>; }
     else                  { <statements>; }

> 3) Better to read.

I don't think so.

> 4) less worries about braket '{'.

More worries about missing 'break;' (bad C heritage)

> 5) ....

....

>
> In Java, C++ we avoided using switch because it ONLY support const&  literal type.
>

D also only supports literals types. A 'switch' statement is often 
implemented as a look-up table when compiled, so keeping the cases a 
compile-time constant helps to generate more efficient code. If you can 
supply an arbitrary condition or a regex, this advantage is lost and 
it's no better than a if/else-if/else chain.

> Most script base language supports things like this. I believe bash shell script
> does. Since D aimed to be a next generation language,
> I suppose that should be in with fall through also.
>

No one forced a "next generation language" have to have a 'switch' with 
conditional or regex cases. Look, Python 3 doesn't even have a 'switch'.