You know, if s2 is short (say, less than 30 or 40 characters), there are worse
things than writing
case A -> s1;
case null -> s2;
default -> s2;
especially if you use spaces (as I just did) to line up the two occurrences of
s2 to make it easy to see they are identical.
And if s2 is long, there are worse things than making a little sub method to
handle it:
case A -> s1;
case null -> frobboz(a, b);
default -> frobboz(a, b);
int frobboz(int a, String b) { … }
And if even THAT is not satisfactory, well, there are worse things than giving
up on the arrows and just using colons (and break, if needed).
Yeah, null makes things uglier, but at least you have your choice of three
different kinds of ugly.
_____________________________________________________________________________________________________
BUT, on the other hand, if we wanted to: instead of, or in addition to,
case pat1, pat2, pat3 -> s;
we could allow the form
case pat1 -> case pat2 -> case pat3 -> s;
which of course could be stacked vertically for visual graciousness and
perspicuity:
case pat1 ->
case pat2 ->
case pat3 -> s;
and such a format would clearly accommodate
case A -> s1;
case null ->
default -> s2;
Con: Could look like a programming error (unintentionally omitted statement),
but that’s also true for the colon forms already permitted.
Con: More verbose than the comma-separated form `case pat1, pat2, pat3 ->`,
which may matter for smallish switch expressions.
Pro: Doesn’t stick `default` in a weird place, or otherwise make a special rule
just to handle “default and null”.
Pro: The keyword `case` appears in front of EVERY individual pattern, making
them easier to see.
Pro: Avoids possible confusion between `case a,b,c ->` and `case (a,b,c) ->`.
Motto: “It’s not fallthrough, it’s just a SwitchBlockStatementGroup.”
> On Apr 20, 2018, at 2:40 PM, Brian Goetz <brian.go...@oracle.com> wrote:
>
> One thing that is relevant to the short term is that now that we killed mixed
> labels, we'd have to have a way to say "case null or default" in arrow world.
> The least stupid thing seems to be to allow default to be tacked on to a
> comma-separated case list as if it were a pattern:
>
> case A -> s1;
> case null, default -> s2;
>
> since you can no longer say:
>
> case A -> s1;
> case null:
> default:
> s2;
