`error[E0038]: the trait `Player` cannot be made into an object
--> src/mankala.rs:7:15
|
7 | players: [dyn Player; 2],
| ^^^^^^^^^^ `Player` cannot be made into an object
|
note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
--> src/mankala.rs:3:40
|
3 | trait Player : Fn(&BoardState) -> u8 + Sized {}
| ------ ^^^^^ ...because it requires `Self: Sized`
| |
| this trait cannot be made into an object...`
I am trying to create a game with 2 players represented as functions each get the board every turn, but they can both be simple functions or closures, so as I understand they need to be dynamic. I am a bit of beginner, so any kind of advice will be helpful. Thanks in advance!
I assume you added Sized to your trait because you first had dyn Player and the compiler complained that it is not Sized. Trait objects (dyn Traits) are not and cannot be Sized since they represent any possible implementation. And adding a Sized constraint means you cannot create dyn Trait at all.
Because of this "unsized"-ness, trait objects can really only be held behind some kind of indirection. In this case you likely want to wrap your players in a Box:
players: [Box<dyn Player>; 2],