But you can also define your own bitfield types to store booleans packed together if you really need to. I would much rather that than have the compiler do it automatically for me.

[–] timhh@programming.dev 23 points 10 months ago (1 children)

Well there are containers that store booleans in single bits (e.g. std::vector<bool> - which was famously a big mistake).

But in the general case you don't want that because it would be slower.

[–] ethancedwards8@programming.dev 7 points 10 months ago (1 children)

Why is this a big mistake? I’m not a c++ person

[–] bitcrafter@programming.dev 5 points 10 months ago (1 children)

The mistake was that they created a type that behaves like an array in every case except for bool, for which they created a special magical version that behaves just subtly different enough that it can break things in confusing ways.

[–] ethancedwards8@programming.dev 2 points 10 months ago (1 children)

Could you provide an example?

[–] timhh@programming.dev 1 points 9 months ago

The biggest problem is that each element doesn't have a unique memory address; iterators aren't just pointers.

[–] gamer@lemm.ee 5 points 10 months ago* (last edited 10 months ago) (1 children)

Consider what the disassembly would look like. There's no fast way to do it.

It's also unnecessary since 8 bytes is a negligible amount in most cases. Serialization is the only real scenario where it matters. (Edit: and embedded)

[–] Croquette@sh.itjust.works 5 points 10 months ago

In embedded, if you are to the point that you need to optimize the bools to reduce the footprint, you fucked up sizing your mcu.

[–] Jankatarch@lemmy.world 4 points 10 months ago

CPUs don't read one bit a a time.

[–] Aux@feddit.uk 0 points 10 months ago

They do, that's the optimisation.