10-May-2013 16:32, deadalnix пишет:
http://www.deadalnix.me/2013/05/10/type-safe-tagged-union-in-d-programming-language/
A trick that I used to use more and more, so I ended up creating a
generic solution and wrote an article about it.
Neat but somewhat limited.
E.g. this is exactly the same switch madness we sought to avoid:
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){ ... }
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.
--
Dmitry Olshansky
