use std::collections::BTreeMap;

struct World {
    entities: Vec<usize>,
    //database: BTreeMap<usize, Box<ReadValue>>,
    database: BTreeMap<usize, Box<ReadEcs<T = SourceInputGateway>>>, // Doesn't work
}

struct SourceInputGateway {
    entity_id: usize,
}

trait ReadValue {
    fn read(&self) -> f32;
}

impl ReadValue for SourceInputGateway {
    fn read(&self) -> f32 {
        0.0
    }
}

trait ReadEcs {
    type T;
    fn read(&self) -> &Self::T;
}

impl ReadEcs for SourceInputGateway {
    type T = SourceInputGateway;
    fn read(&self) -> &Self::T {
        self
    }
}