On 13 February 2012 01:15, Hite, Christopher <Christopher.Hite@partner.commerzbank.com> wrote:
We could be having the same conversation about optional<bool>. Here the documentation is clear: it works as expected but is the user probably should be using tri-state.
Why? The poster child is database access, where every field can be set or unset, and every set field has a value. Why would anyone want to special case access to bool to use a different type?
We could optimize optional<bool> to store ~0 to indicate unset.
Could you elaborate? I don't see how, at least not without changing the interface, as a "dereferenced" optional<bool> has to return a reference to bool whose address cannot change. Please look at vector<bool> to see the trouble caused when people changed the generic interface for a specific type.
As far as I can tell optional<T&> is a type which can be easily confused with optional<T>, but is really equivalent to T*. It also allows for debates about the meaning of reassignment.
If there are debates about about the meaning of reassignment, then it really is NOT equivalent to T*.
I'm not dead set against this optimization. I'm just wondering if anyone will really benefit and if it's worth adding a specialization + tests.
Do you honestly think it is more work than was put into writing your email message (let alone all the future threads that will inevitably keep coming up)? -- Nevin ":-)" Liber <mailto:nevin@eviloverlord.com> (847) 691-1404