On 06/21/2010 04:15 PM, Don wrote:
Jonathan M Davis wrote:
Sean Kelly wrote:
Jonathan M Davis Wrote:
In any case, that means that it could be made required to have a
control
statement at the end of a case block without having to specify a
specific
destination for fallthrough - though I'd prefer "continue switch" over
"goto case" since it's more explicit and less error prone (since
there's
no doubt that you didn't intend to put a destination for the goto if
you
use "continue switch" instead of a "goto case" without a destination).
It's a small thing, but I think "continue switch" could be
misleading. Consider this:
switch (getState()) {
case X:
setState(Z);
continue switch;
case Y:
break;
case Z:
writeln( "done!" );
}
Having never encountered D before, what would be your interpretation of
this code?
I hadn't thought of that. That could be a source of confusion.
However, since a switch statement isn't a loop, and it's not a
construct in any other language AFAIK, the person will look it up.
Once you've looked it up, I don't think that it would be particularly
hard to remember what it actually does. It's quite clear what's going
once you've become familiar with the construct and is quite
unambiguous in comparison to "goto case" which could easily be missing
the target case rather than being meant for fallthrough.
So, perhaps it's not immediately intuitive, but many language
constructs are, and I think that it's fairly clear once you've looked
it up. Having something like "fallthrough" or "goto next case" would
of course be even clearer, but those would require new keywords. I
still think that "continue switch" would be clearer than "goto case"
as well as less error prone. Personally, I think that the fact that
it's less error prone alone makes it a better choice even if it were
somewhat less clear.
- Jonathan M Davis
But 'goto case XXX' is an extremely rarely encountered construct, that
screams 'Examine this code closely'. So I don't think it needs extra
error checking.
After Sean's example, goto case XXX is my fave for fallthrough. I don't
like unlabeled "goto case" to mean fall through, it's one of those "need
to look in the manual" features. goto case XXX is generalized fall through.
Andrei
