Fernando Cacciola <fernando.cacciola <at> gmail.com> writes:
[skip] Or are you saying that, since supporting such a requirement is not entirely possible since in the end is up to T, it isn't worth doing the best optional<T> itself can?
Yes, that's what I'm saying except that I tend to disagree with the word "best" in this part of your sentence "doing the best optional<T> itself can" :) I believe, based on my reading of documentation, that my proposal is more correct.
I don't care about lexical_cast here
OK, but you two clearly care for extracting an optional<T> from a stream that was insterted a bare T instead of an optional<T>.
You're right. Current version of boost doesn't support this lexical_cast< optional<int> >(0) but I'm going to make a special case when TargetType is optional<T> to return a default value rather than throwing an exception: lexical_cast< optional<int> >("not a number").get_value_or(0); Since it's a special case, I can easily avoid using optional_io.hpp. Alex