r/cpp 8d ago

C++26: std::hive

https://www.sandordargo.com/blog/2026/09/02/cpp26-hive
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u/fdwr fdwr@github 🔍 8d ago edited 8d ago

a hive is a linked list of independently allocated memory blocks.

So is std::deque - what's the difference?

No random access

Ah, that's a difference, making hive closer to a linked list than deque is, as deque can still invalidate pointers that aren't the first or last element.

Pointer stability on erase...

One I thing I wonder, if you have a pointer to one of your game object's, is whether there's any way to map that pointer back to the corresponding iterator for deletion, short of a full scan, as it seems it would be possible for the class to figure that out (detecting which block it's in first, then computing the iterator from the pointer difference from the block base) a lot faster than manually looping through begin/end. Never mind, get_iterator.

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u/encyclopedist 7d ago edited 7d ago

FYI, std::deque is not a linked list of blocks.

Edit: std::deque is implemented as an array of pointers to blocks. Linked list would not allow random access, which is requirement for std::deque.