Lionello Lunesu wrote:
Andrei Alexandrescu wrote:
Steven Schveighoffer wrote:
Another idea is to make the T the ref'd arg, similar to how the
system call read() works:
bool popNext(ref T);
This has some benefits:
1) you aren't checking a temporary for emptyness, so it fits well
within a loop construct
2) you can avoid returning a dummy element in the empty range case.
3) you avoid returning a piece of possibly large data on the stack
when it's probably just going to get copied anyways (although the
compiler can sometimes optimize this).
We considered that as well. It is problematic because looking at
elements always entails copying them, which is rather silly if you do
it for e.g. an array.
By golly, I kid you not but the interface I personally like the most is:
struct ArchetypalInputRange(T)
{
T* popNext();
}
popNext returns a pointer to a T (the value may be reused) or null
when the range is done. Iteration becomes easy and efficient for all
types. An input range would still have to keep a buffer (and return a
pointer to it), but things are not awkward to implement.
Given the bad reputation that pointers have, I guess people wouldn't
like this all that much.
You don't need a pointer to T, you need a nullable T :)
...which doesn't exist...
You need a nullable reference to T...
Andrei
