I’ve been working on a platformer game in rust. Game objects are stored in a Vec, and each is updated independently. However, a given object would like to interact with other objects. In C I would do something like fn update(&mut self, others: &mut [Self]). However, this would result in the parameters being aliased, which is not allowed.
What I’m looking for is some type that acts like a &mut [T], but remembers which element it is not allowed to access. I could use two &mut [T] values, built with split_at_mut, but this is unwieldy. I could make a struct that contains both. Is there a crate that does this? Ideally it would use unsafe internally so the compiler knows there is exactly one element in between. (that is to say, I would prefer something using only 24 bytes)
Chain does not do what I want because it can only be used as an iterator, not for indexing. To be clear, I would like to be able to index the result exactly like a &mut [T], except that it will find the element under consideration to be out of range.
Does your function need to accept
&mut self? If you can redesign that function just to take the slice of game objects (fn update(objs: &mut [T])) then you don’t need to worry about the aliasing at all. You can pass an index as well if you want to operate on them one at a time.This is actually closer to the strategy you’d see with ECS. You’d operate not on individual objects, but on all relevant objects at once.