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Document number: N3873

Date: 2014-01-20

Improved insertion interface for unique-key maps

by Thomas Köppe

Excerpt:

The existing interface of unique-keyed map containers (std::map, std::unordered_map) is slightly underspecified, which makes certain container mutations more complicated to write than necessary. This proposal is to add new specialized algorithms:

• emplace_stable(): if the key already exists, does not insert and does not modify the arguments.
• emplace_or_update(): inserts or updates the mapped element if the key already exists.