C++26: std::hive

This article discusses the proposed std::hive feature for C++26, detailing its purpose and potential impact on the language. It provides insights into the design and implementation considerations for this new feature.

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In a recent article on std::inplace_vector , I mentioned that C++26 is generous with new containers. Here’s the other one: std::hive .

Consider a game engine managing thousands of entities. Each entity is stored in a container, and other subsystems hold pointers to those entities. When an entity is destroyed, you erase it from the container. With std::vector , every element after the erased one shifts, invalidating every pointer. With std::list , pointers survive but cache performance suffers.

std::hive gives you both: stable pointers and iterators that survive insertions and erasures, O(1) amortized insertion and erasure, and good cache locality thanks to contiguous memory blocks. It’s available in the new <hive> header, introduced by P0447R28 . If the name sounds unfamiliar but the…

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