Trait DispatchConst 

pub trait DispatchConst {
    type Constant;

    const CONST: Self::Constant;
}

A dispatch of a constant.

Prefer using the dispatch_const macro unless the dispatcher will be used several times.

Examples

#[derive(Debug, Default, PartialEq, Eq)]
struct Painting(Vec<usize>);
impl Painting {
    fn draw(&mut self, stroke: usize) {
        self.0.push(2 * stroke)
    }
}
#[derive(Debug, Default, PartialEq, Eq)]
struct Photoshop(Vec<usize>);
impl Photoshop {
    fn draw(&mut self, filter: usize) {
        self.0.push(5 * filter)
    }
}

#[derive(Default)]
struct Dispatcher<T>(PhantomData<T>);

impl DispatchConst for Dispatcher<Painting> {
    type Constant = usize;
    const CONST: Self::Constant = 5;
}
impl DispatchConst for Dispatcher<Photoshop> {
    type Constant = usize;
    const CONST: Self::Constant = 3;
}

struct SingleStrokeMasterpiece;

#[impl_dispatch({Painting; Photoshop})]
impl<A> Into<A> for SingleStrokeMasterpiece {
    fn into(self) -> A {
        let mut drawing = A::default();
        drawing.draw(Dispatcher::<A>::CONST);
        drawing
    }
}

let painting: Painting = SingleStrokeMasterpiece.into();
let photoshop: Photoshop = SingleStrokeMasterpiece.into();
assert_eq!(painting, Painting(vec![10]));
assert_eq!(photoshop, Photoshop(vec![15]));

Required Associated Constants

const CONST: Self::Constant

The constant.

Required Associated Types

type Constant

The type of the constant.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors