Bill Baxter wrote:
On Mon, Nov 16, 2009 at 9:30 AM, KennyTM~ <kenn...@gmail.com> wrote:
On Nov 17, 09 01:12, Bill Baxter wrote:
On Mon, Nov 16, 2009 at 8:24 AM, Andrei Alexandrescu
<seewebsiteforem...@erdani.org> wrote:
Walter Bright wrote:
Andrei Alexandrescu wrote:
I was hoping the lesson learned would be to fix switch as was
suggested.
I checked, because it wasn't written in the way I usually write things,
and sure enough it wasn't code I wrote :-)
From the changelog for D 0.129: "Incorporated Ben Hinkle's new
std.format
which can print general arrays."
http://www.digitalmars.com/d/1.0/changelog1.html#new0129
So people are liable to make the mistake.
Andrei
What about when you want to fall through to a multiple label? Or a range
label?
case 0:
// do stuff
goto case ??;
case 1: .. case 9:
// do more stuff
goto case ??;
case 10,20,30:
// still more stuff
The obvious answer would seem to be just "pick any one".
I just bring it up because I haven't seen that ... uh case ...
mentioned by anyone.
--bb
Since
case a:
..
case b:
expands to
case a:
case a+1:
case a+2:
// ....
case b:
and
case a,b,c,d:
expands to
case a:
case b:
case c:
case d:
Your speculation is correct. Please note that the "goto case X;" statement
works *now*, so there's no need to guess its behavior.
Seriously? Didn't realize.
So valid end-of-case statements would be:
break;
return;
continue;
goto *;
goto case *;
And if you don't have one of those then it's an error?
throw *;
Could this get into difficult-to-verify territory? And therefore be
difficult to implement?
It looks like the exact same problem as enforcing that all code paths
return a value, which is something I think D doesn't currently enforce
because it's too hard. So you run into Walter's dislike for
errors/warnings that are incorrect because the compiler is too stupid.
It could enter difficult territory if the rule was:
if (condition) break;
and leave it to the compiler to prove that condition is always true.
That's not the case with the proposed change. All control flow
statements you enumerated above transfer flow unconditionally.
Andrei
