P3091 R3 Better lookups for `map` and `unordered_map`

[wg21bot]

P3091R0 Better lookups for map and unordered_map (Pablo Halpern)

[billy-baker]

P3091R0: Better lookups for map and unordered_map

P3091R0: Better lookups for map and unordered_map

2024-02-27 Library Evolution Telecon Minutes

Champion: Pablo Halpern

Chair: Billy Baker

Minute Taker: Inbal Levi

Start: 2024-02-27 18:00 UTC

Does this paper have:

• Why this facility should go into the standard library? Yes
• Examples? Yes
• Field experience?
  • Implementation experience? Yes
  • Usage experience?
  • Deployment experience?
• Performance considerations?
• Discussion of prior art?
• Changes Library Evolution previously requested?
• Support for "std::format", "hash", and allocators (if required)? N/A
• Wording? Yes
• Feature test macro? No
• Freestanding? No

Pros:

Cons:

Open Questions:

Key Insights:

Poll Ideas:

POLL: This is a problem worth solving.

Attendance: 11

# of Authors: 1

Outcome: Unanimous consent to continue pursuing.

POLL: The alternative design with a smaller container API and extensions to std::optional should be pursued.

SF	WF	N	WA	SA
6	4	0	0	0

Attendance: 11

# of Authors: 1

Author Position: SF

Outcome: Unanimous consent.

Action Items:

End: 19:00 UTC

Summary

Based on the first poll, the problem is worth solving. The second poll
showed that an alternative design is desired rather than the R0 design.
There was some preference expressed to apply to other containers such
as vector.

Next Steps

Provide a revised version that includes a feature test macro and that changes
the design to use std::optional.

[phalpern]

A new version of this paper, P3091R1 proposes the optional<T&> alternative, including changes to optional. It also adds the missing feature-test macros.

[wg21bot]

P3091R1 Better lookups for map and unordered_map (Pablo Halpern)

[wg21bot]

P3091R2 Better lookups for map and unordered_map (Pablo Halpern)