On Wednesday, 23 October 2013 at 16:27:47 UTC, Ali Çehreli wrote:
On 10/23/2013 02:55 AM, simendsjo wrote:
Illegal code is accepted in static if, but not in enum
declarations.
This leads to having three lines when one is enough. Is this
just an
oversight, or by design?
template T(alias A) {
enum T = true;
}
void main() {
struct S { }
static if(__traits(compiles, S.a) && T!(S.a)) // ok
enum e1 = true;
else
enum e1 = false;
enum e2 = __traits(compiles, S.a) && T!(S.a); // No
property S.a
}
I don't know whether it is even specified but it feels like a
feature to me.
Just like the shortcut behavior of runtime if helps with
avoiding illegal memory accesses, this helps with avoiding
illegal code altogether:
// null access avoided
if ((p !is null) && (p.member == 42))
// illegal code avoided
static if (__traits(compiles, S.a) && (S.a == 42))
Ali
The question is if it would make sense to allow it for enum as
well as static if. As enum is a compile-time constant I think it
would be consistent.
