Re: [boost] [optional] Feedback on the range interface for Boost.Optional

Every feature should be well motivated by a real use case or a set of use cases. I don't find any of the examples in this proposal motivating. In fact, this feature seems to encourage bad code, judging by the examples: - using transform(f) | join with an optional-returning function f, instead of using a simple filter(predicate) - materializing optionals when not really necessary (incurs extra moves/copies) - abusing the range-for loop for unwrapping optionals Best regards, Thomas