We’ve already asked one of the questions on side effects (though not sure we
agreed on the answer): what if the dtor throws? The working story is that the
exception is wrapped in a MatchException. (I know you don’t like this, but
let’s not rehash the same arguments.)
Wrapping exceptions into a MatchException destroy any idea of refactoring from
a cascade of if ... instanceof to a switch.
I think refactoring is a use case we should support.
Wrapping exceptions thrown from dtors does not affect refactoring.
If I have:
if (x instanceof D(P)) A;
else if (x instanceof D(Q)) B;
else C;
and I refactor to
switch (x) {
case D(P): A; break;
case D(Q): B; break;
default: C
}
Let's imagine that dtor D throws. The wrapping happens when a
dtor/accessor is invoked _implicitly_ as a result of evaluating a
pattern match. In both cases, we will wrap the thrown exception and
throw MatchException. In this way, both instanceof and switch are
"clients of" pattern matching, and it is pattern matching that throws.
I don't see any destruction here.
