Re: [boost] compact_optional -- prompting interest

2015-09-29 9:11 GMT+02:00 Gonzalo BG :

@Andrzej: Right now your implementation allows constructing a compact_optional from the sentinel value, which results in an empty compact_optional. What is the motivation for this?

In my fork I've disabled it for the following reasons: - I'd rather use compact_optional's default constructor to explicitly state that i'm constructing an empty optional, this made it easier to reason about my code, - the other constructors from value_type can then hint the compiler that the compact_optional is not empty (but I did not profile so I don't know if this has any impact at all).

The motivation for this was to enable an integration of compact_optional with older/other parts of the program that still use magical values: ``` using Index = compact_optional> string s = /*...*/ Index i {s.find("substr")}; ``` In the above example, I will not be changing std, but want to change to compact_optional as soon as possible. But in fact, I could provide a dedicated conversion function for this use case. This aspect is still under consideration, so I may go with your suggestion. Regards, &rzej