P1255 R14 A view of 0 or 1 elements: views::nullable And a concept to constrain maybes

[jensmaurer]

P1255R1 A view of 0 or 1 elements: view::maybe (Steve Downey)

[jensmaurer]

P1255R2 A view of 0 or 1 elements: view::maybe (Steve Downey)

[wg21bot]

P1255R3 A view of 0 or 1 elements: view::maybe (Steve Downey)

[wg21bot]

P1255R4 A view of 0 or 1 elements: view::maybe (Steve Downey)

[brycelelbach]

Kona 2019-02 LEWGI Minutes

P1255R2 std::view::maybe

Champion: Steve Downey

Minute Taker: Guy Davidson

Start Overview: 8:10

Start Discussion: 8:32

Is a function pointer Nullable?

Should a pointer to uninitialized memory satisfy the semantics of it.

Add maybe_view?

Start Polling: 8:55

POLL: When we ship std::view::maybe, Nullable should be a normative concept, knowing that our time is scarce and this will leave less time for other work.

Strongly For	Weakly For	Neutral	Weakly Against	Strongly Against
1	4	4	3	0

Attendance: 15

POLL: std::view::maybe’s reference capture semantics should be consistent with std::view::single.

Strongly For	Weakly For	Neutral	Weakly Against	Strongly Against
4	2	5	1	0

Attendance: 15

Volunteers to Help Write Wording: Nathan Myers, Alisdair Meredith (post meeting), Matt Calabrese (post meeting)

End: 8:58

CONSENSUS: Bring a revision of P1255R2, with the guidance below, to LEWGI for further design review.

• Add wording.
• Add a Nullable named type requirement.
• Make std::view::maybe's reference capture semantics consistent with std::view::single.

[brycelelbach]

Cologne 2019-07 LEWGI Minutes

P1255R4 std::view::maybe: Design Review

Champion: JeanHeyd Meneide

Minute Taker: Phillip Ratzloff

Start Overview: 07-18 8:44

Add tony tables for LEWG.

Start Review: 9:00

Start Polling: 9:12

• Fix the typo'd maybe_view constructor outside of the maybe_view; it should be the factory function maybe.
• s/semiregularbox/semiregular-box/.
• Remove conditional noexceptness from the constructors (consistent with single_view), and call LEWG's attention to this.
• Use unwrap_ref instead of the exposition-only maybe_unwrap.
• Call LEWG's attention to the use of ptrdiff_t as the return type of size (which is consistent with single_view).
• s/is_reference_wrapper/is_reference_wrapper_v/.

POLL: We should promise more committee time to pursuing P1255R4, with the guidance above, and forward it to LEWG for C++23, knowing that our time is scarce and this will leave less time for other work.

NO OBJECTION TO UNANIMOUS CONSENT.

Attendance: 13

End: 9:16

CONSENSUS: LEWGI sends P1255R4, with the guidance below, to LEWG, for C++23.

• Fix the typo'd maybe_view constructor outside of the maybe_view; it should be the factory function maybe.
• s/semiregularbox/semiregular-box/.
• Remove conditional noexceptness from the constructors (consistent with single_view), and call LEWG's attention to this.
• Use unwrap_ref instead of the exposition-only maybe_unwrap.
• Call LEWG's attention to the use of ptrdiff_t as the return type of size (which is consistent with single_view).
• s/is_reference_wrapper/is_reference_wrapper_v/.