On Friday, 10 May 2013 at 13:11:37 UTC, Dmitry Olshansky wrote:
E.g. this is exactly the same switch madness we sought to avoid:
The article don't plan to avoid this, but to make the tagged
union safe. I agree this is a plus, but didn't really took time
to make that work.
void process(T)(T data) {
alias Type = typeof(data);
static if(is(Type == A)) {
// Code that handle the case where it is an A.
} else static if(is(Type == B)) {
// Code that handle the case where it is an B.
} else {
static assert(0, "You must handle type " ~
Type.stringof);
}
}
t.apply!process();
I'd rather see another idiom supported too:
t.apply!(processA, processB)();
where e.g.
void proccessA(A value){ ... }
void processB(B value){ ... }
That can work indeed.
Anther thing is that will allow succinct notations like:
int squared = t.apply!(
(A a) => a.x*a.x + a.y*a.y,
(B b) => b.x*b.x + b.y*b.y + b.z*b.z
)();
I sure don't fancy putting static if into lambdas.
Another thing about it is it allows specifying safe catch all
or default case.
That last one won't work. DMD don't accept locals here, even if
they are functions.
