Allow the use of std::optional in C++2017

[SeanFarrow]

It would be good if std::optional were used in projects that use C++2017.

A define like that which is available in boost.dll 1.70 would suffice in my opinion.

[jeking3]

Could you be more specific, perhaps provide an example use?

[SeanFarrow]

This isn’t something that is user facing. Within the boost format library boost::optional is used, what I’m asking for is a define to use std::optional instead, like boost.dll does with boost/std::filesystem. If I get a chance next week, I’ll create a PR. From: James E. King III <[email protected]> Sent: 19 April 2019 11:56 To: boostorg/format <[email protected]> Cc: Sean Farrow <[email protected]>; Author <[email protected]> Subject: Re: [boostorg/format] Allow the use of std::optional in C++2017 (#63) Could you be more specific, perhaps provide an example use? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub<#63 (comment)>, or mute the thread<https://github.com/notifications/unsubscribe-auth/AALDK7XI7HTCAB3JGGRASRLPRGQLNANCNFSM4HCJOEGQ>.

[AraHaan]

Isn't there an language macro that is defined the the compiler supports the standard optional instead of the boost one that can be checked against like there is with CXX_LIB_FILESYSTEM/CXX_LIB_EXPERIMENTAL_FILESYSTEM or something along those lines that can be used with boost?

(unrelated but I want to also figure out things I can use in place of format and wformat used in this lib so that way a program of mine could be made a bit more optimized.)

(hmm so is

typedef lagged_fibonacci_01_engine<double, 48, 607, 273> lagged_fibonacci607;

the same as this?

std::subtract_with_carry_engine<double, 48, 607, 273>

)