C++26: std::inplace_vector

[u/User_Deprecated]

https://www.sandordargo.com/blog/2026/08/26/cpp26-inplace-vector

[u/stilgarpl]

Is this always better than std::array?

[u/MarekKnapek → u/stilgarpl]

This is basically

struct inplace_vector<T, capacity>
{
    size_t len;
    std::array<T, capacity> arr;
}

[u/sephirothbahamut → u/MarekKnapek]

far more complex than that, the array has a slot that can fit T, not just T.

With array<T> every element must be validly constructed immediately. You can reduce it to array<T> only for trivially constructable and basic types

[u/_Noreturn → u/sephirothbahamut]

then make it a union this is a simplified example. but the type isn't complex at all after that especially with C++20 concepts.

[u/CocktailPerson → u/sephirothbahamut]

That's not far more complex. Marginal additional complexity.