Use Cow to make this fully Iterator compliant

[flo-l]

Just leaving this here as a note to myself.

[flo-l]

docs: https://doc.rust-lang.org/std/borrow/enum.Cow.html

[flo-l]

using this would give users cheap immutable references to the original data and clones if they use multiple windows.

maybe a custom Cow like smartpointer or a wrapper is needed. One which can be turned into a Clone as soon as two of them exist simultaneously

[flo-l]

the window smartpointer needs either a negative send bound or some sort of synchronization

[flo-l]

what should be done if mutation happens while another, overlapping window is still reachable?

[flo-l]

it's not possible to clone the older window as soon as another one gets spawned by next(), because window derefs to (maybe multiple) references, which cannot be changed.

Instead one could create another storage vec and store the new and following windows there. But that's a performance nightmare..

[flo-l]

Derefs are gone with v3.0, maybe it's possible now