On 10/9/13 10:07 AM, monarch_dodra wrote:
On Wednesday, 9 October 2013 at 16:34:52 UTC, BLM768 wrote:
On Wednesday, 9 October 2013 at 06:48:31 UTC, monarch_dodra wrote:
OK, so that's two functions already. What about opCmp? What about
toHash?
Since ordered comparisons make no sense with null values, opCmp would
need to throw an exception when working with null values anyway.
That's exactly what it does right now. I've considered the other
operators, and the same logic seems to apply to them.
As for toHash, that needs to be overloaded whenever opEquals is.
That's true for all types.
What if T is a range? Then "Nullable!T.empty" should return true if
the Nullable is empty. IF we don't, we'll get a crash in foreach.
It does. Null is not an "empty" range; it's the _absence_ of a range.
They are not the same concept, and a null range _cannot_ be empty
because the range does not exist. Therefore, it's a logic error and
should throw an exception.
That was my point. Writting "Nullable!T == T" is the exact same thing:
Comparison of a value with the absence of a value. It's neither equal
nor different, it's an error.
I'm confused. I thought Nullable!T == T is well defined to mean "true"
if a value is present and equal to the right-hand side, or "false"
otherwise (the absence of a value is a singularity unequal with all
objects). What's harmful about that?
Andrei
